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E L N E C
Copyright (c) 1990-96 by Roy W. Lewallen, W7EL
For Version 3.0 27 January 1996
1
C O N T E N T S
I N T R O D U C T I O N . . . . . . . . . . . . . . . . . . . . . . . 4
ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . 5
A FEW WORDS ABOUT COPY PROTECTION . . . . . . . . . . . . . . . 5
LICENSE, COPYRIGHT, AND WARRANTY NOTICE . . . . . . . . . . . . 6
GUARANTEE . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
ABOUT THIS MANUAL . . . . . . . . . . . . . . . . . . . . . . . 6
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . 7
HARDWARE REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . 9
MEMORY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . 10
THE MAXIMUM PULSE OPTION (MAXP) . . . . . . . . . . . . . . . . 10
G E T T I N G S T A R T E D . . . . . . . . . . . . . . . . . . . 12
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . 13
RUNNING ENSETUP . . . . . . . . . . . . . . . . . . . . . . . . 13
U P G R A D I N G F R O M E A R L I E R V E R S I O N S . . 17
NEW FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . 18
UPGRADING . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
M O D E L I N G W I T H E L N E C . . . . . . . . . . . . . . . 20
INTRODUCTION TO MODELING . . . . . . . . . . . . . . . . . . . . 21
MODELING THE ANTENNA STRUCTURE . . . . . . . . . . . . . . . . . 21
CONSIDERATIONS FOR MODELING WIRES . . . . . . . . . . . . . . . 23
Wires Joining at an Angle . . . . . . . . . . . . . . . . . 23
Closely Spaced Wires . . . . . . . . . . . . . . . . . . . 24
Quads . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Log Periodic Antennas . . . . . . . . . . . . . . . . . . . 24
Multiband Antennas . . . . . . . . . . . . . . . . . . . . 25
USING SOURCES . . . . . . . . . . . . . . . . . . . . . . . . . 25
Phased Arrays . . . . . . . . . . . . . . . . . . . . . . . 26
Using Multiple Sources . . . . . . . . . . . . . . . . . . 26
USING LOADS . . . . . . . . . . . . . . . . . . . . . . . . . . 26
MODELING GROUND . . . . . . . . . . . . . . . . . . . . . . . . 27
INTERPRETING THE RESULTS . . . . . . . . . . . . . . . . . . . . 28
Patterns . . . . . . . . . . . . . . . . . . . . . . . . . 28
Source (Feedpoint) Impedance and SWR . . . . . . . . . . . 29
Currents . . . . . . . . . . . . . . . . . . . . . . . . . 30
Load Data . . . . . . . . . . . . . . . . . . . . . . . . . 31
TIPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Speeding Up Computation By Removing the Memory Manager . . 31
Doubling the Number of Available "Pulses" . . . . . . . . . 32
Segment Tapering for Wires Joining at an Angle . . . . . . 32
Sources and Loads at Junctions of More Than Two Wires . . . 33
2
Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Conductivity and Scaling . . . . . . . . . . . . . . . . . 33
Using Templates . . . . . . . . . . . . . . . . . . . . . . 34
Modeling Complex Structures . . . . . . . . . . . . . . . . 34
WHY NOT DBD? . . . . . . . . . . . . . . . . . . . . . . . . . . 34
R U N N I N G E L N E C . . . . . . . . . . . . . . . . . . . . . 36
STARTING ELNEC . . . . . . . . . . . . . . . . . . . . . . . . . 37
STARTING ELNEC IN TRACEVIEW MODE . . . . . . . . . . . . . . . . 37
TEST DRIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Along the Straightaway . . . . . . . . . . . . . . . . . . 38
Through the Curves . . . . . . . . . . . . . . . . . . . . 41
R E F E R E N C E M A N U A L . . . . . . . . . . . . . . . . . . 46
GENERAL INFORMATION AND CONVENTIONS . . . . . . . . . . . . . . 47
THE MENUS . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
The Main Menu . . . . . . . . . . . . . . . . . . . . . . . 48
The Options Menu . . . . . . . . . . . . . . . . . . . . . 55
The Wires Menu . . . . . . . . . . . . . . . . . . . . . . 58
The Sources Menu . . . . . . . . . . . . . . . . . . . . . 64
The Loads Menu . . . . . . . . . . . . . . . . . . . . . . 66
The Media Menu . . . . . . . . . . . . . . . . . . . . . . 67
The Plot Menu . . . . . . . . . . . . . . . . . . . . . . . 70
The View Antenna Display and Menu . . . . . . . . . . . . . 71
Frequency Sweep and the Frequency Sweep Menu . . . . . . . 78
GROUP EDIT . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
SAVING, RECALLING, AND DELETING FILES . . . . . . . . . . . . . 84
SAVING AND RECALLING ANTENNA DESCRIPTIONS . . . . . . . . . . . 85
TRACEVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Starting TraceView . . . . . . . . . . . . . . . . . . . . 86
ANALYZE and TraceView . . . . . . . . . . . . . . . . . . . 86
Changing the Primary Trace . . . . . . . . . . . . . . . . 87
Ending TraceView . . . . . . . . . . . . . . . . . . . . . 87
ELNEC FILES . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Files on the Distribution Disk(s) . . . . . . . . . . . . . 88
Files Created by ELNEC and/or ENSETUP . . . . . . . . . . . 88
MICROSMITH . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
PRINTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
PLOTTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
PROBLEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
ERROR MESSAGES . . . . . . . . . . . . . . . . . . . . . . . . . 94
PULSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
NOTES FOR EXPERIENCED MININEC USERS . . . . . . . . . . . . . 100
MORE MININEC INFORMATION . . . . . . . . . . . . . . . . . . . 101
HELP! . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
3
E L N E C
I N T R O D U C T I O N
4
ACKNOWLEDGEMENTS
The fundamental computation portion of this program is that of MININEC
(Version 3) by J.C. Logan and J.W. Rockway of the Naval Ocean Systems
Center.
Special thanks are due the beta testers for version 3. They are Paul
Carr, N4PC; Dick Gardner, N1AYW; Ernie Guerri, W6MGI; Linley Gumm,
K7HFD; Jerry Hall, K1TD; Dick Kiefer, K0DK; Jim Sanford, WB4GCS; and
Roger Steyaert, K7RXV. Wes Hayward, W7ZOI, was instrumental in
developing ELNEC's ability to write files for the MicroSmith program.
The efforts of these people were vital to the goal of making ELNEC a
bug-free program and in improving its usability.
Previous versions of ELNEC were tested by Jim Bromley, W5GYJ; John
Brosnahan, W0UN; Paul Carr, N4PC; Bill Clarke, WA4BLC; Tony DeBiasi,
K2SG; Dick Gardner, N1AYW; Ernie Guerri, W6MGI; Ed Hanlon; Wes
Hayward, W7ZOI; Dick Kiefer, K0DK; Doug McGarrett, WA2SAY; Bob
Rullman, K7MSH; and Roger Steyaert, K7RXV. In addition to testing,
they made many suggestions for improvements to ELNEC and the manual,
many of which were implemented. ELNEC is a much better program due to
their efforts.
Thanks to all the ELNEC users who took the time to send in their
suggestions. Finally, but foremost, thanks to my family for being
understanding and supportive during the many, many hours I've spent
away from them working on this program.
A FEW WORDS ABOUT COPY PROTECTION
A friend of mine made the observation that a conscience is kind of
like a little wheel with sharp teeth that spins and digs into you. But
each time it does, he said, the teeth wear down a little so the next
time it's not quite as sharp. Eventually, if you use it enough, there
aren't any teeth left. If the teeth on your wheel are worn all the way
down, what I'm about to say won't reach you anyway so you may as well
skip the rest of this section.
Copy protection is a big nuisance to both the user and the software
developer. It also can necessitate an increase in price. That's a
lousy deal -- more nuisance for a higher price. That's why this
software is not copy protected. Yet copying it is easier than ripping
off a Walkman from K-Mart, with zero chance of getting caught
(although it's just as illegal and dishonest). So it's pretty risky to
5
put the product out without copy protection. I'm well aware that
sellers of similar programs have had to copy-protect their programs to
prevent such theft. Theft? You bet! Literally hundreds of hours
(many weeks of full-time work) have gone into developing this program
and refining it to make it useful and easy for you to use. (Other
expenses, like advertising, aren't cheap either!) So please, when
someone asks you for a copy of the program, realize that he or she is
asking you to steal. Politely say no, but give them the name and
address where they can order a copy. It's a bargain at the price,
it'll save future users more nuisance and a higher price, and it'll
save the wear on your conscience wheel. Thanks.
LICENSE, COPYRIGHT, AND WARRANTY NOTICE
Now for the official words. ELNEC is NOT a "shareware" or "freeware"
program. The purchaser is licensed to use this program "like a book".
The program may be used by other people, or used on more than one
machine, but just like a book can be read by only one person at a
time, the program may be used by only one person on one machine at a
time. If you purchased a second "type" (coprocessor or non-
coprocessor) at less than full price, only one type may be used at one
time. (That is, both types count as one copy.) Copies may be made
only for backup use by the purchaser or for use as described above.
This software is copyright (c) 1990 - 1993 by Roy W. Lewallen. All
rights are reserved. No express or implied warranties are granted
regarding the fitness of this program or manual for any purpose,
except as stated in the paragraph immediately following.
GUARANTEE
If you're not satisfied with ELNEC, I'll promptly return the full
purchase price.
ABOUT THIS MANUAL
A glance at this manual might give the impression that ELNEC is a
complex, difficult-to-use program. Nothing is farther from the truth!
In all likelihood, you'll be able to begin analyzing antennas with
just a few minutes' familiarization (Try the TEST DRIVE). If you've
used MININEC or other MININEC-based programs, you'll find ELNEC to be
worlds easier and friendlier. But inevitably you'll want to learn all
the shortcuts and features built into ELNEC, or will have a question
about the operation or meaning of some function or menu selection.
6
This manual is written so you'll have the answers at your fingertips,
whenever you need them.
DESCRIPTION
ELNEC is a powerful but easy-to-use program for modeling and analyzing
antennas. A wide variety of antenna types and parasitic structures may
be modeled.
The far-field pattern of an antenna, including gain, can be plotted on
an ARRL-type (logarithmic-dB) or linear-dB polar plot, or presented in
tabular form. All outputs, including plots, can be printed on a
standard dot-matrix printer or HP LaserJet or DeskJet printer. A
special ANALYZE feature tells you the forward gain, front-to-back or
front-to-side ratio, beamwidth, angles of 3-dB pattern points, major
sidelobe level, and front-to-sidelobe ratio. The points which ANALYZE
finds can be included on the plot to verify that ANALYZE has measured
what you thought it had. In addition, you can display or print the
voltage, current, impedance, and SWR (for a 50- or 75-ohm system) at
each excitation source, the voltage, current, impedance, and power
loss of each load, and the current distribution on each wire. The
antenna description may also be printed.
ELNEC offers an easy, menu-based system for describing and modifying
the antenna. Unlike MININEC, ELNEC doesn't require a tedious and
error-prone counting of "pulses" to determine where a source or load
is placed. And once placed, the source or load stays where it belongs
when the antenna is modified. (This feature is described in more
detail in the REFERENCE chapter, p. 46.) Many special features are
included to make modifications fast and simple; for example, wires can
be added, deleted, or tilted, or wire lengths or antenna height
changed, with a few keystrokes.
Antenna descriptions and patterns are easily saved and recalled from
disk files.
ELNEC is substantially faster than MININEC3, and is several times
faster yet if a coprocessor is available (see HARDWARE REQUIREMENTS,
p. 9).
ELNEC has many other features, just a very few of which are:
- Inclusion of true current, as well as voltage, sources.
7
- Three-dimensional View Antenna feature graphically shows what the
antenna looks like, with currents and pattern superimposed if
desired.
- Ability to superimpose several patterns on a single grid to
compare antennas and see the effect of changes.
- Frequency sweep capability.
- Inclusion of wire loss if desired.
- Ability to save patterns.
- Ability to save computed arrays so that later you can begin where
you left off.
- Many shortcuts for entering the antenna description, including
tilting wires and changing wire length.
- Advanced editing features, allowing you to copy, add, or delete
groups of wires, sources, loads, or media.
- Far-field (pattern) analysis and plots/tables can be restricted
to any range of angles to speed computation when only one portion
of the pattern is of interest.
- ANALYZE features (beamwidth, sidelobe level, etc.) can be
calculated with greater angular resolution than the resolution of
the far-field analysis.
- All choices are made within ELNEC; it's not necessary to leave
the program to change features or descriptions. (Exception: printer
type, default file subdirectory, and screen colors are defined with
a setup program.)
- ELNEC is "lazy" -- it calculates only what it has to, so no
calculation is unnecessarily repeated. Many antenna changes don't
require complete recalculation, so results are fast after making
modifications.
- Ability to handle very complex antennas with the addition of the
Maximum Pulse Option (MaxP).
- Correction of several MININEC3 "bugs". ELNEC correctly calculates
the field from grounded antennas, while MININEC3 incorrectly
calculates the field from grounded segments. ELNEC improves
8
MININEC3's capability to model closely-spaced wires. Problems with
certain wire orientations (e.g. sloped wires in the X = -Y plane)
have been eliminated.
HARDWARE REQUIREMENTS
ELNEC is designed to run on all IBM-PC compatible computers running
under DOS 2.0 or higher which have a hard disk drive and at least 640k
of RAM. Unlike MININEC, ELNEC doesn't have a fixed limit on the number
of wires, sources, loads, etc. (Exception: total number of "pulses" is
limited to 127 unless used with the Maximum Pulse Option (MaxP),
separately purchased -- see PULSES, P. 100). As a result, the memory
(RAM) requirements depend on how elaborate an antenna you wish to
model. At least 512k of RAM is recommended, with 640k being sufficient
for the most elaborate antenna. If you don't have sufficient RAM for a
particular antenna, ELNEC won't crash; it'll notify you before
attempting to do the analysis. See MEMORY CONSIDERATIONS, p. 10.
ELNEC requires a CGA, EGA, MCGA, VGA, or Hercules graphics system. To
provide the highest possible resolution, CGA plots are monochrome.
Text printing can be done with a printer connected to the parallel
printer port. An Epson MX or FX 8/9-pin, IBM Proprinter 8/9 pin, Epson
LQ 24-pin, HP LaserJet or DeskJet, or compatible printer is required
for printing of the graphics plot. Most modern printers are compatible
with one of these types. Plotters are not supported.
Two types of ELNEC are available: STD (Coprocessor), and N (No
coprocessor). The N type runs substantially faster than MININEC3, but
isn't speeded up if a coprocessor is present. The STD type
requires a coprocessor and is 5-6 times faster than the N type. I
highly recommend that you consider investing in a coprocessor if you
use calculation-intensive programs like ELNEC, CAD or graphics
programs, or spreadsheets. The cost is moderate, installation is
simple, and the performance increase is striking.
ELNEC is not copy-protected so can be installed on a hard disk simply
by copying the files.
9
MEMORY CONSIDERATIONS
The amount of memory ELNEC requires is determined by the complexity of
the antenna being modeled, the most significant factor being the total
number of wire segments. (See "Modeling The Antenna Structure", p. 21,
for more information on segments.) Due to the limitations of the
compiler used, ELNEC accesses only the bottom 640k of RAM, or
"conventional" RAM. With most systems having 640k of RAM, adequate RAM
will be available for analyzing nearly any antenna. However, you might
encounter occasions when ELNEC reports insufficient available RAM.
Possible reasons are discussed next.
Conventional RAM is used by DOS and several other things such as
"resident" (sometimes called "TSR" for Terminate-Stay-Resident)
programs. These are programs which can be called up with a "hot key";
Sidekick and PCTools (when installed as resident) are examples.
Spoolers, disk caches, virtual (RAM) disks, expanded memory managers,
and device drivers (e.g., HPIB drivers) can also occupy conventional
RAM. These can be unloaded or moved to free more RAM. Products such a
QEMM, 386Max, and DOS v. 5 permit moving some or all of these out of
the conventional memory area in machines equipped with 80386 or higher
processors and >640k RAM. DOS v. 5 and later can also be made to move
itself out of conventional RAM in machines with 80286 or higher
processors and >640k RAM. This frees a significant amount of RAM.
Before ELNEC begins calculations, it checks to see if enough RAM is
available. If not, it reports the amount which must be freed. If this
occurs, the antenna complexity must be reduced or the program must be
exited and RAM-consuming programs or drivers must be unloaded. (If
this is done, the program will remember the antenna configuration and
restore it when the program is restarted.) If you have 640k of RAM,
you should never see the insufficient memory message unless a
significant amount of RAM is occupied by other programs or drivers.
ELNEC uses only the lower 640k of RAM; it does not access expanded or
extended memory. This limitation is imposed by the compiler used.
THE MAXIMUM PULSE OPTION (MAXP)
An auxiliary program is available to increase the number of total
pulses (see PULSES, P. 100) ELNEC can handle. This is the Maximum
Pulse Option (MaxP). It is sold separately. It's available only in a
coprocessor version and requires a hard disk, at least 640k RAM, and
ELNEC version 2.20 or higher. (It doesn't use extended or expanded
memory.) With MaxP installed, ELNEC operates normally with antennas
10
having 127 or fewer pulses. When more pulses are specified, MaxP is
automatically called. The calculation speed of MaxP is about 2-4 times
slower than that of ELNEC, so computation time can be lengthy. Bear in
mind also that the calculation time increases approximately as the
square of the total number of pulses. These reasons are why MaxP is
offered only in a coprocessor version. If you're interested in MaxP,
consult current advertisements or contact me for information.
11
E L N E C
G E T T I N G S T A R T E D
12
INSTALLATION
Due to program size, use of ELNEC without a hard disk isn't
recommended.
If your program was furnished on a 3.5 inch disk or high density (1.2
Meg) 5.25 inch disk, all files are on the single disk. If your program
was supplied on two disks, all files except the ELNEC program file
ELNEC.EXE are on the one marked "MANUAL". The other disk contains only
ELNEC.EXE. You will have two ELNEC.EXE disks if you purchased both
coprocessor and non-coprocessor types, and may receive only the
ELNEC.EXE disk if you have purchased a second type.
The first step for all users is to copy the distribution disk(s) and
put the distribution disk(s) away. Use the copy for the remainder of
the installation procedure. This copy will be called "the working
copy".
To install ELNEC on a hard disk, create a subdirectory (suggested name
ELNEC) and copy all the files from the working copy to the
subdirectory. You can delete READ.ME, and ELNEC.DOC (this file) after
printing it, to save disk space. I suggest printing ANTNOTES.DOC which
contains information about the example antennas, after which it can
also be deleted. You can delete MSHERC.COM if you don't have a
Hercules graphics system. If you want to keep the antenna files
(extension ".EN") and trace files (extensions ".ENT" and ".F(#)") in a
separate subdirectory (for example, \ELNEC\ANT), move them to the
other subdirectory. You can tell ELNEC where to find them by entering
the path in ENSETUP (next section) or in ELNEC's Options Menu.
Create a subdirectory under your new ELNEC subdirectory (such as
\ELNEC\DATA) for data output files. Frequency sweep outputs as well as
any outputs you save in files will be saved here after you tell ELNEC
where to put them (see the Options Menu section, p. 55, for details).
RUNNING ENSETUP
ENSETUP changes some of the values stored in file ELNEC.CFG, which
ELNEC reads each time it's started (see ELNEC FILES, p. 87). Other
values are modified from the Options Menu within ELNEC. Parameters
which you can modify with ENSETUP are:
Printer type (8/9- or 24-pin dot-matrix, or HP DeskJet or LaserJet
printers)
Printer port (parallel ports only, LPT1: through LPT4:)
13
Path for antenna (.EN) and trace (.ENT) files (tells ELNEC where
to find them)
Date format (mm-dd-yyyy, dd-mm-yyyy, or yyyy-mm-dd)
Background color (background color for text displays on color
monitors)
Plot colors (effective only with EGA/VGA systems -- CGA plots are
monochrome)
Recalled trace colors (effective only with EGA/VGA systems)
Monitor type (required only if you have a monochrome or LCD monitor
connected to a color adapter)
Maximum number of MicroSmith .DAT file frequency steps (only of
interest if you have the MicroSmith program)
The default values are:
8/9-pin Epson FX type dot-matrix printer
Printer port LPT1:
Antenna (.EN) files and trace (.ENT) files on the current drive, in
current subdirectory
U.S. convention date format (mm-dd-yyyy)
Black background
Plot grid, total field plots white
Horizontal polarization plot green
Vertical polarization plot red
Recalled traces assorted colors
Monitor type automatically determined by ELNEC
Maximum of eight frequency steps in MicroSmith .DAT files
If the default values are satisfactory, you don't need to run ENSETUP.
To start ENSETUP, go to the ELNEC subdirectory by typing 'CD ELNEC'.
Then type 'ENSETUP'.
Printer type
Five choices are currently available. If you don't know which type of
printer yours will emulate, choose 8/9 pin Epson FX type. Most modern
8/9-pin printers will emulate the Epson FX, most 24-pin printers the
Epson LQ, and most laser printers the HP LaserJet. You can't damage
your printer by selecting the wrong type, but you might get some very
strange-looking plots!
Dot Matrix Printers: If you have either an 8/9 or 24 pin IBM
Proprinter, use the Epson MX driver. (Only 8-pin resolution will be
available for the 24-pin Proprinter.) Otherwise, observe the following
recommendations. In general, use the Epson LQ (24-pin) driver if you
14
are using a 24-pin printer, and the Epson FX driver for an 8/9 pin
printer. There are two choices of drivers for 8/9 pin printers. The
Epson MX driver uses fewer graphics density options than the FX.
Therefore it will work with a wider variety of printers, including IBM
8/9 and 24 pin printers. The plot it generates is somewhat smaller
than FX driver plots, but you may get a faster plot with this driver
on FX-compatible printers depending on your printer and computer
hardware. Note that there are some dot-matrix printers which don't
imitate the Epson printers. See PROBLEMS, p. 90.
Laser Printers: If you are using an HP LaserJet III later printer or
compatible, you can use either the LaserJet or DeskJet/LaserJet III
drivers. The two drivers use different formats to send data to the
printer, so one may be faster than the other depending on your
computer hardware. If you have a LaserJet, LaserJet II(), LaserJet
2000 or compatible, select the LaserJet driver.
DeskJet Printers: Select the DeskJet/LaserJet III driver if you are
using an HP DeskJet printer.
Plotters: ELNEC does not support plotters.
Printer port
Leave this setting at LPT1: (parallel port 1) unless your printer is
connected to a different parallel port.
Path for antenna (.EN) files
If you want to keep the antenna (.EN) and trace (.ENT) files on a
different drive or subdirectory than the program file (ELNEC.EXE),
you'll need to enter their location. As an example suppose that
ELNEC.EXE is in subdirectory ELNEC and the antenna files are in a
subdirectory of ELNEC named ANTFILES. The most foolproof way to enter
the path is to specify the full path from the root directory
(C:\ELNEC\ANTFILES for the example). This path can also be changed in
ELNEC's Options Menu.
Background color
This parameter will change the background color of the text display on
color monitors. It does not change the background color of the plot.
If you have a monochrome monitor, select Black.
15
Other colors
These select colors for the various parts of the plot. CGA PLOTS ARE
MONOCHROME, so color choices are useful only for EGA/VGA monitors.
Hercules and some other monochrome systems won't support bright white,
and will display in standard intensity even if bright white is chosen.
Monitor type
If "Automatically determined" (the default) is selected, ELNEC will
assume that the monitor is color if a CGA, EGA, or VGA adapter is
present and monochrome if the adapter is Hercules. If you're using a
monochrome monitor with a color adapter, some colors may not appear on
the monitor. In this case, make the "Monochrome" selection. The "LCD"
selection does the same thing as "Monochrome" but modifies the
calculation progress "thermometer" display which may otherwise not
reproduce properly.
Maximum number of MicroSmith .DAT file frequency steps
This choice is of interest only if you also have a MicroSmith program.
(See p. 89 for more information about MicroSmith.) MicroSmith versions
2.000B and earlier were able to handle only 8 frequency steps in an
imported .DAT file. If you have version 2.000B or earlier, leave the
value of this selection at its default value of 8. If you have version
2.000C or later, set the value of this selection to 100 unless told
differently by your MicroSmith documentation.
Save choices and exit
If you make this selection, the choices you've made will be saved in
ELNEC.CFG.
Exit without saving changes
If you make this selection, ELNEC.CFG won't be changed.
16
E L N E C
U P G R A D I N G F R O M E A R L I E R V E R S I O N S
17
NEW FEATURES
ELNEC version 3 includes several new features not present in earlier
versions. The new features are:
Improved View Antenna - See p. 71.
Frequency Sweep - See p. 78.
Group Edit - See p. 82.
Preserve Connections - See p. 62.
Scrolling displays - When you send outputs (e.g., source data) to the
screen, you can now scroll up and down through the data rather than
having it appear only one screen at a time. The scrolling feature is
activated also if the list of description or trace files is too large
to fit on a single screen.
File Browse - You can recall any ASCII file and "browse" (view, with
scrolling features) it from within ELNEC. This is particularly useful
for viewing the output from a frequency sweep, which is put in an
ASCII file.
Parallel Wire Correction - A solution has been found to the problem of
close parallel wires requiring a large number of segments and is
implemented in ELNEC v.3. You must enable this feature to have it take
effect. See the Options Menu section, p. 55, for details.
Grounded segment correction - MININEC3 contained a "bug" which
incorrectly added the field from a grounded wire segment when the
antenna is modeled over real ground. ELNEC has corrected this bug.
Consequently, results from this version of ELNEC may differ slightly
from those from earlier versions. The difference occurs only when
modeling a grounded antenna over real ground, is most apparent when a
small number of segments is used, and is most noticeable when ground
conductivity is poor. Because of the correction, this version of ELNEC
will correctly report a zero field at zero elevation angle for
grounded vertical antennas over real ground; earlier versions reported
a non-zero value. The zero result is correct, since ELNEC doesn't
model ground wave propagation.
18
UPGRADING
All you need to do to update ELNEC is to replace your older ELNEC.EXE
and ENSETUP.EXE files with the files of the same names from version 3.
(The new ENSETUP has two new options. You can now set the parallel
printer port if desired. Also, it is used to set ELNEC's MicroSmith
file output to be compatible with various MicroSmith versions.) If you
also have MaxP, replace MAXP.EXE with the new version. Begin, as
always, by making a copy of your distribution disk(s) and use the copy
for all operations. It's not necessary to run ENSETUP. It is suggested
that you create a new subdirectory for ELNEC data output files and use
the Options Menu to specify it as the output file path. All version 1,
2, 2.2, and 3 programs and files are completely compatible except that
MaxP v.1.02 or later must be used with ELNEC version 3. Be sure to
read the rest of this manual for information about how to take full
advantage of the new features. Please note that in some cases ELNEC
version 3 may give slightly different results than earlier versions
due to the new parallel wire and grounded segment corrections.
If you have a color monitor, run ENSETUP and note the colors shown for
recalled traces. If these are all white, select some different colors.
These colors will also be used for Frequency Sweep traces.
19
E L N E C
M O D E L I N G W I T H E L N E C
20
INTRODUCTION TO MODELING
You may already use modeling as a tool without realizing it. When you
draw plans for a room for your house, the lines are straight and the
dimensions exact. When the room is finished, none of the features is
exactly like the plans -- but the plans were close enough for you to
plan what materials to get and how to put them together, and whether
the room would suit the desired purpose. Likewise, a schedule of the
day's activities is an idealized model of what will really come to
pass (and sometimes it's a pretty poor one, too!) ELNEC is a tool for
antenna modeling -- building a model of antenna which will imitate the
real thing.
Is it really possible to predict how an antenna will behave by
building a model and analyzing it? You bet! But HOW ACCURATELY can
we predict its behavior? That depends on the kit of tools that's
provided and the skill of the person making the model. In this chapter
I'll discuss some of the strengths and limitations of ELNEC's "tool
kit" and give some guidance to help you build your modeling skill.
The limitations of the MININEC modeling code (which, except for the
close parallel wire limitation, are shared by ELNEC) are discussed at
length in "MININEC: The Other Edge of the Sword", in February, 1991
QST.
You may want to take the "Test Drive" in the next chapter before or
during the reading of this chapter.
MODELING THE ANTENNA STRUCTURE
ELNEC models every antenna as a collection of straight WIRES. I'll
emphasize STRAIGHT, again; a round loop must be built out of short,
straight pieces of wire. You're free to choose the diameter of each
wire, and the program will give accurate results with diameters from
as small as you wish up to at least 0.02 wavelengths (that's about 3
feet at 40 meters). With some imagination, nearly any type of
conducting structure can be modeled as wires. For example, a wall can
be modeled as a grid of wires with a mesh on the order of 0.1
wavelength or less.
You tell ELNEC where the wires are placed in space by giving their x,
y, and z coordinates relative to a universal origin, or 0,0,0 point.
(See the first part of the REFERENCE MANUAL chapter, p. 46 for an
illustration of the axis system.) Until you get used to this
description method, a sketch may help. ELNEC has several features to
21
make this job as easy as possible; they're described in the REFERENCE
MANUAL chapter, p. 46. Wires can be connected only at their ends;
crossing wires won't connect them. Modeling an "X" - shaped structure
requires four wires if the crossmembers are connected at the center of
the "X".
Wires are connected whenever an end of both have the same coordinates.
If a ground plane (either perfect or "real") is used, a wire is
connected to ground if its z coordinate is zero.
Each wire is divided into SEGMENTS for analysis purposes. ELNEC
assumes that the current is constant from the center of one segment to
the center of the adjacent segment. This makes the problem one of
finding a finite number of impedances, currents, and field strength
contributions. You, the user, must choose the number of segments for
each wire, and this is where some of the skill part of modeling comes
in. Although accuracy improves when more segments are specified,
computation time increases approximately as the square of the number
of segments. A useful rule of thumb is 10 segments per half wavelength
for pattern/gain analysis, and perhaps twice that number if really
accurate impedance values are required. Very closely-spaced wires or
wires joining at acute angles may require many more segments (see the
next section). If in doubt, a straightforward way of telling whether
enough have been specified is to increase the number and see if the
results change. When analyzing antennas with wires which are closely
spaced or which join at acute angles, you might also look at the
currents on the wires. Abrupt current changes may indicate an
insufficient number of pulses (but note that apparently abrupt phase
reversals at junctions may be due to internal conventions of assigning
current direction -- see INTERPRETING THE RESULTS, p. 28). Determining
a reasonable number of segments isn't as hard as it sounds. You'll
soon get a good feel for about how many you need to get the shape of a
pattern or a feedpoint impedance with the accuracy you need.
MININEC documentation specifies that the segment length should be
greater than 1.25 times the wire diameter, and greater than .0001
wavelength. Another rule which should be observed for best accuracy is
that the segment lengths of connecting wires shouldn't differ by more
than a factor of about 2.
22
CONSIDERATIONS FOR MODELING WIRES
General
Wires can be connected only at their ends. This is done automatically
if the end coordinates of the wires are equal. Serious errors will
occur if wires cross or occupy the same space. Modeling a wire grid
like the following
o----o----o----o
| | | |
| | | |
| | | |
o----o----o----o
| | | |
| | | |
| | | |
o----o----o----o
cannot be done with fewer than 17 wires. Wire junctions are shown as
"o".
Wires Joining at an Angle
It's best to have approximately equal segment lengths in wires joining
at an angle. Wires joining at a right angle require slightly more
segments than a single straight wire or wires joining in a straight
line. A good working number for single square one-wavelength (quad)
loops is six segments per side. Four may be used without noticeably
changing the pattern of a single loop. More than six are required if
more than one element is involved or if highly accurate feedpoint
impedance results are required. See "Quads", below.
Wires joining at an acute angle require many more segments. This is
because of the method MININEC uses to handle wire connections. A
method to reduce the total number of required segments is described in
the TIPS section below.
Large-diameter wires joining at an acute angle (or one wire at an
acute angle to ground) can have a special problem because of too SHORT
a segment at the intersection. Imagine two pieces of tubing joining at
an acute angle, merged so that their outer edges touch. The line of
intersection will have a significant length. If this line of
intersection is on the order of a segment length, ELNEC can give an
erroneous answer. The problem is helped considerably by the Parallel
Wire Correction, but can still occur. Viewing the currents will reveal
23
a sudden increase in current at the one or two segments closest to the
intersection. It may or may not have a significant effect on the
pattern or impedance.
Closely Spaced Wires
Closely-spaced wires can now be modeled without special
considerations, provided that ELNEC's Parallel Wire Correction is on.
Check the Options Menu to determine its status. (There may still be
limits - always check your answers and look for strange behavior of
currents.) It is recommended that the Parallel Wire Correction be left
on at all times.
Quads
Experiments indicate that quads require quite a large number of
segments (perhaps 12 or more per loop side) to give a reasonable
representation of front-to-back ratio. When dealing with wires
connected at an angle, MININEC (and ELNEC) "cuts the corner" by half a
segment length. This doesn't cause much error with single loops but
causes enough change in the currents in parasitic elements to quite
noticeably affect indicated front-to-back ratio. The forward pattern
and gain are fairly accurate with 6 segments/side or so. The segment-
tapering method (see TIPS, p. 31) is a very effective way of improving
the accuracy of front-to-back indications. To adjust quad loop size
after tapering, adjust the length of the center wire of each side.
Adjust the loop spacing by using the Group Edit features.
Log Periodic Antennas
An integral part of log periodic antennas is the transmission line
connecting the elements. This must included in the model, since no
valid assumptions can be made about the relative voltages and currents
at the element centers. Example descriptions are included with the
program. Read the file ANTNOTES.DOC for more information about the
examples. Although the feedlines intersect the elements at a right
angle, the low-Q nature of the log-periodic antenna makes segment
tapering unnecessary.
24
Multiband Antennas
ELNEC is well-suited for modeling multiband antennas. Don't forget to
pay attention to the segment length, however. Remember that as you
increase the frequency the segment length increases in terms of
wavelength. In general, you should double the number of segments each
time you double the frequency. A bare minimum number of segments for a
square (quad) loop is about four per quarter wavelength. This means
four segments per side at the frequency at which the loop is a full
wavelength in circumference, eight per side at twice the frequency,
etc. Consequently, a quad loop which is one wavelength at 3.5 MHz
can't accurately be modeled at 28 MHz or above because of ELNEC's
limit of 127 pulses unless you use segment tapering, (p. 32, 62), the
pulse-doubling technique (p. 32), or the Maximum Pulse Option
(available separately). (A loop has the same number of pulses as
segments.)
"Crossed dipoles"
To model two dipoles fed at a common point (sometimes called "crossed
dipoles", feed by inserting a wire between the pairs of dipole halves
and place the source on the wire:
. .
\ /
\ /
\__0__/
dipole halves / \ dipole halves
/ ^ \
/ source \
. .
USING SOURCES
Unlike MININEC, source placement is easy with ELNEC (see the REFERENCE
MANUAL chapter, p. 46, for details). Sources appear in series with the
wire at the specified point. Both current and voltage sources are
available. The type of source can make a large difference in the
performance of phased arrays, but will make no difference if the
antenna contains only one source.
25
Phased Arrays
Because of the number of segments required, it may not be practical to
model phased array transmission line feed systems with ELNEC. However,
ELNEC permits you force the array elements to have any ratio of
voltages or currents and will tell you the resulting impedances. This
is the information required to design a feed system to actually
accomplish the assumed voltage or current ratio. Phased arrays
generally require currents to be in a specified ratio, and ELNEC
provides true current sources.
Using Multiple Sources
Some precautions must be taken when using multiple sources in an
antenna. The phase of resulting currents can be 180 degrees from where
you intended. This can be prevented in phased arrays of parallel wires
by making sure that end 1 of the wires are all facing the same
direction (for example, all wire end 1's of a vertical array connected
to ground). Reversing a wire will reverse the effective polarity of
all sources in that wire. An ambiguity can arise when placing a source
at a wire junction because the polarity can depend on which wire the
source "belongs" to and which way this wire is facing. A source is
always placed so the positive terminal (or terminal of outward-flowing
current) faces end 2 of the wire in which it's placed. A source placed
on a junction of two wires "belongs" to the higher-numbered wire, even
if ELNEC reports it to be connected to a specified lower-numbered
wire. Therefore, it will be placed with the positive terminal facing
end 2 of the higher-numbered wire. Ambiguity can be avoided by making
the wires face the same direction by connecting them end 1-to-end 2.
If more than two wires are connected at a common point, the source
always will "belong" to the specified wire and will have its positive
terminal facing end 2. Whenever you use multiple sources in any
antenna other than simple, parallel wires, it's highly recommended
that you look at the currents in the wires and make sure they're
really flowing in the direction you thought. See "Currents" under
INTERPRETING THE RESULTS, p. 28.
USING LOADS
Lumped impedances can be inserted into the wires if desired. Like
sources, these are easy to place with ELNEC, and appear in series with
the wire. Loads are useful to simulate loading coils, capacitors in
capacitive-loaded antennas, traps, and losses. They can be specified
as either an impedance in R + jX form or as a quotient of Laplace
transform polynomials. Automatic conversion of series or parallel RLC
26
circuits to Laplace transform coefficients is provided. More detail is
given in the REFERENCE MANUAL chapter, p. 46.
Loading coils frequently have a significant amount of loss which
should be included in the model. Measurement is the best way of
determining the loss, but even a guess may be adequate. Air-wound
inductors typically have Q's in the range of 200-400 or so. This means
that you can estimate the equivalent series R as about 1/200 to 1/400
the reactance. If putting in this range of values impacts your result,
you may want to make a measurement or better estimate of the Q.
A trap is resonant at only one frequency, but trap antennas are
operated at other frequencies as well. The only way to accurately
model the trap is either by measuring its impedance at each frequency
of interest, or by knowing the equivalent L, C, and R components, and
how R varies with frequency. These in turn must be measured unless you
can talk the manufacturer out of this information (or have constructed
the trap yourself out of known components). Traps frequently will
cause a couple of dB loss at one frequency or another, so failure to
include loss resistance will lead to overly optimistic results.
MODELING GROUND
ELNEC provides free space, ideal ground, or "real" ground
environments.
You'll find the following statement repeated several times in this
manual: If either a perfect or "real" ground is specified, ELNEC
assumes a perfect ground for impedance and current calculations. The
"real" ground description is used only for determining the shape and
strength of the far field (pattern). This means that you cannot
determine the efficiency of a ground radial system with ELNEC, and the
impedances given for low (lower than about 0.2 wavelengths) horizontal
antennas won't be correct. (Impedances will be those seen over
perfect, not real, ground). Specifically, the resistive part of the
impedance of low horizontal antennas will be unrealistically low,
which also results in incorrectly high reported gain. ELNEC shares
this limitation with MININEC and all other MININEC-based programs. The
limitation was consciously made by the authors of MININEC to keep the
code size and computation time reasonable.
Note that the pattern of a low horizontal antenna will have the
correct shape (although the reported impedance and gain will be wrong)
provided that all parts of the antenna are at the same height.
27
What ELNEC will tell you is what happens to your signal as the result
of ground absorption or partial reflection due to finite ground
conductivity and permittivity. This is valuable in determining the
best height for an antenna, and you'll learn a lot about the
limitations of vertical antennas unless they're near a hillside or
lake.
The ground may be broken into several "MEDIA", each having its own
conductivity and dielectric constant (relative permittivity). Each
medium can be a different height, permitting modeling of hills and
other features. However, ELNEC won't recognize any shielding caused by
ground features -- it looks for a point of reflection from the ground
and ignores any features in between the antenna and the reflection
point or beyond the reflection point. The media can be arranged in
parallel slices or concentric rings. If rings are chosen, you can put
radials in the innermost circle. These radials modify the ground
conductivity in that region, again only for far field (pattern)
analysis. See the REFERENCE MANUAL chapter, p. 46, for an example of
the use of several media.
A Wire is connected to ground by specifying a zero z-coordinate.
INTERPRETING THE RESULTS
Patterns
An antenna radiates in three dimensions but pattern plots have only
two. This poses a problem not unlike that faced by cartographers
making flat maps of the spherical Earth. ELNEC uses a standard method
of representing the pattern, with elevation and azimuth plots. For
both types, the antenna is assumed to be so far away it's represented
only by a point at the center of the plot.
To see how an azimuth plot is generated, visualize one of those
conical paper cups with a pointed bottom. Now imagine it being much,
much larger than the antenna. With the tip of the cup bottom on the
antenna, place yourself on the rim of the cup with a field strength
meter. As you traverse the rim of the cup, take readings and plot them
on a polar graph. If you start directly over the +x axis, the first
reading is plotted at zero degrees. The reading halfway around the rim
is 180 degrees, and so forth. The "elevation angle" is the angle the
side of the cup makes with the ground. To measure the pattern at a
lower elevation angle, the cup is made more squat.
28
For the elevation pattern, slice a flat plate in half, leaving a
semicircle. Make the half-plate much larger than the antenna, and
place it on edge with the straight side on the ground and the antenna
at the center of the straight side. Again you're on the rim taking
readings and plotting. If the bottom of the half-plate is on the x-
axis and you're on the rim at the ground in the +x direction, the
reading is for zero degrees elevation. The reading from the top of the
rim, directly over the antenna, is 90 degrees elevation. The "azimuth
angle" is the angle the half-plate bottom makes with the x-axis. For
example, if the plate, still on edge, is rotated so it lines up with
the y-axis, the azimuth angle is 90 degrees.
Looking at the pattern on the View Antenna display will help you
visualize it. After calculating a pattern, go to the View Antenna
display and press 'T' twice to see the pattern as a semi-solid figure.
ELNEC does not model ground-wave propagation. The far-field
observation point is assumed to be a large distance away, beyond which
the ground wave signal has disappeared. Consequently, the field shown
for vertical antennas over other than perfect ground will always be
zero amplitude at the horizon (zero elevation angle). The field from
horizontal antennas is zero at zero elevation angle regardless of
ground type. This is because horizontally-polarized waves are
perfectly reflected with a phase inversion from any ground type, if
the grazing angle is zero.
Source (Feedpoint) Impedance and SWR
The impedance, SWR, voltage, and current at each source can be viewed
or printed by selecting 'SD' (Source Data) from the Main Menu. If
ELNEC reports a very low value of resistance at any source, be careful
-- this might indicate operation beyond ELNEC's limits. For example,
ELNEC will report low resistances for low horizontal antennas over any
type of ground (See MODELING GROUND, p. 27). If two elements are
closely spaced and fed out of phase (W8JK-type antennas), the low
resistance is real but the real antenna might not work like ELNEC
predicts unless you have included wire loss (a Main Menu choice).
Losses become important when the resistance is low, so be sure wire
loss is included if a low resistance is indicated. Negative
resistances sometimes are reported for multi-element arrays. These
actually can occur but are subject to the same cautions as low
positive resistances.
The SWR shown is the SWR which would be present on a feedline
connected in place of the source. Values are given for 50 ohm and
29
user-defined feedlines. This is directly calculated from the source
impedance.
Currents
The currents at each pulse (segment junction) can be displayed with
the View Antenna feature ('VA' from the Main Menu or 'V' from the
Wires Menu) or seen in tabular form by selecting 'CU' from the Main
Menu. The currents give important information about antenna operation.
In addition, they're invaluable in assessing whether the antenna is
working as intended and in spotting conditions where ELNEC is being
used beyond its capabilities.
One thing to look for is symmetry. If the antenna is symmetrical, the
currents also should be -- if not, some error has been made in wire
definition, source placement, or other area. For example, the current
from the vertical part of a ground plane antenna should split evenly
among the radials if the radials are the same length and evenly
spaced. Make it a habit to look for these symmetries and you'll spot
problems before bad results lead you astray.
Positive current is defined as flow from end 1 to end 2 of a wire.
Another thing to look for is abrupt and unexplained current changes
(instead of a smooth change from one pulse to the next). This usually
is due to not having enough segments but may be due to some other
factor causing ELNEC to be operating beyond its limits. Sudden current
reversals may be no cause for concern as they might be due to the way
you've defined the wires. Positive current flow always is defined as
being from end 1 to end 2, so if you've connected two end 1's or two
end 2's together you'll see a 180-degree shift in current direction at
the junction of the wires (provided you have the View Antenna phase
information on or are looking at the currents in tabular form). The
current actually is continuous as it should be, but the definition of
direction changes from one wire to the other. There's nothing wrong
with connecting wires in this fashion but don't be confused by the
currents ELNEC shows as a result. Watch for this also when using
multiple sources -- see "Using Multiple Sources", p. 26.
Current phase information can be included on the View Antenna display,
but it frequently conceals important information about what's
happening to the magnitude of the currents. See the section on the
View Antenna Display, p. 71, for more information about this feature.
The importance of currents is underscored by the fact that the field
generated by a wire is proportional to the current flowing on it. If
30
one element of a Yagi antenna shows a small current relative to the
others, it's not contributing much to the overall field. It may,
however, be generating just enough to deepen a null in the pattern. If
your model contains several nearby wires, towers, and other objects, a
look at the currents on them will quickly tell you whether they're
having an effect on your antenna's performance. If the current on an
object is small relative to the current on your antenna, you generally
can remove it from the model without much impact on the result.
Shorter conductors require more current than long ones to have the
same effect.
Load Data
Load data are shown by typing 'LD' at the Main Menu. The voltage
across, current through, impedance of, and power loss of each load is
shown. In addition, the total load loss is shown in watts and dB. The
loss figures are invaluable in determining the loss caused by traps,
loading coils, and the like. You also can determine the voltage across
the load or current through it under actual operating conditions. Note
the total applied power reported by ELNEC. The voltage across or
current through the load at a given power input will be the reported
voltage or current multiplied by the square of the ratio of the power
you'll be applying to the total power ELNEC is reporting.
TIPS
Speeding Up Computation By Removing the Memory Manager
This tip applies only to the STD (coprocessor) type. If your computer
has extended or expanded memory, you probably are using an
extended/expanded memory manager. Common ones are EMM386, QEMM386, and
386MAX. ELNEC and MaxP don't use extended or expanded memory, and
calculations can be made faster by a factor of 2-4 by not loading a
memory manager. According to Microsoft, this is true for coprocessor
floating-point operations done by any program compiled with any
Microsoft compiler. (I have no information about other brands.) The
manager is installed with a statement in the CONFIG.SYS file like
DEVICE=C:\DOS\EMM386.EXE. Computation speed can be increased by
preventing the driver from being loaded. To do so, you must delete
this line or precede it with REM. Please don't attempt this or the
following step unless you have a good understanding of what you're
doing and what it will take to restore your system. Any lines in the
CONFIG.SYS and AUTOEXEC.BAT which use the memory manager to load
resident programs or device drivers into high memory must also be
modified to load these items conventionally. (DOS may still be loaded
31
high if you're using DOS 5.0 or higher, since doing so doesn't require
a memory manager.) Refer to your memory manager documentation for
details. The computer must be re-booted to make the changes effective.
The memory manager must be restored before running any application
which uses extended or expanded memory. It's up to you to decide if
the increased speed is worth the inconvenience of modifying the
AUTOEXEC.BAT and CONFIG.SYS files and the possible reduction of
conventional RAM space.
Doubling the Number of Available "Pulses"
The limit of 127 "pulses" can be effectively doubled in some cases.
(See PULSES, p. 100, for more information on pulses.) The
requirements are that the antenna (including sources and loads) is
symmetrical, and that only free-space analysis is desired. If these
are true, one-half the antenna can be modeled over a perfect ground,
and the result will be the same as the whole antenna modeled in free
space. (Note, however, that the reported gain will be 3 dB higher,
since all the antenna's power is concentrated in one hemisphere.) A
simple example of this principle is a quarter-wavelength vertical over
a ground plane, which has the same pattern as a free-space dipole.
Segment Tapering for Wires Joining at an Angle
Wires joining at an angle must have shorter segments than single
straight wires or wires joining in a line. This is because of the way
MININEC handles the currents at wire junctions. The straightforward
solution in this situation is to increase the number of segments.
However, doing so increases computation time and may require more than
the permitted maximum of 127 total pulses. The technique described
here provides high accuracy with a smaller total number of pulses or
segments.
Instead of making the entire wires out of short segments, the segments
can be made short near the junction, tapering to a longer length away
from the junction. ELNEC automates this process but it's useful to
know how the procedure works so you can optimize it for your
particular purpose. The basic procedure is to replace the original
wire with several wires of different lengths. The new wire closest to
the junction is made very short and with one segment. The second wire
is made twice the length of the first, also with one segment. This
process is continued until the segment length becomes long enough
(say, 1/20 wavelength), and the remainder of the original wire is made
up of a multiple-segment wire of approximately this segment length. In
the automated process, you can choose the minimum and maximum segment
lengths or use the default values of 1/400 and 1/20 wavelength. More
32
information can be found in the REFERENCE MANUAL, under "The Wires
Menu", p. 58.
Sources and Loads at Junctions of More Than Two Wires
If you want to place a source or load on a wire end which is connected
to more than one other wire, the wire containing the source or load
can't have the lowest number of the group. For example, if you have
five wires arranged as a ground plane antenna with four radials and
want to place a source at the base of the vertical wire, the vertical
wire can't be wire number 1. This is due to the way the basic MININEC
code assigns "pulse" numbers. Unlike MININEC or other MININEC-based
programs, ELNEC will warn you if it's unable to place a source or load
where requested due to this cause. Since there's no way within the
structure of MININEC or ELNEC to place a source or load at the end of
the first of a group of wires connected to a common point, the only
solution is to renumber the wire (see "The Wires Menu", p. 58) or
avoid making the wire containing the source/load the lowest numbered
of the group connected to the common junction. (No problem exists if
only two wires are connected together.)
Scaling
The antenna can be scaled for another frequency if some cautions are
observed. The method is to go to the Main Menu, choose Wavelengths for
UNITS, and change the frequency as desired. When the frequency is
chosen, ELNEC will ask whether you want the antenna to stay the same
in terms of meters or wavelengths. Choose (w)avelengths. This will
scale the antenna so that the wire end coordinates (which includes
scaling of height above ground) and media height and boundaries remain
the same in terms of wavelength at the new frequency. The wire
diameter and radial wire diameter will be scaled ONLY IF THE DIAMETERS
AREN'T SPECIFIED AS WIRE GAUGE. Wire and ground conductivity aren't
scaled by this process; see "Conductivity and Scaling", below.
Conductivity and Scaling
If you're modeling your antenna over "real" ground at other than the
actual frequency of use, the ground conductivity and wire loss (as
well as wire and radial length and diameter) must be scaled for
accurate results. The conductivity of the ground or wire should be
changed in direct proportion to the frequency. For example, if the
actual antenna operates at a frequency of 7 MHz over ground with .001
S/m conductivity, it can be accurately modeled at 299.8 MHz if the
ground conductivity is changed to 299.8 / 7 * .001 S/m. Dielectric
33
constant should not be scaled. Failure to correctly scale ground
conductivity generally will be evident only at very low angles.
Using Templates
It's usually faster to make modifications to an existing antenna than
to describe one from scratch. Save some typical examples of the types
of antennas you frequently model and recall them as starting points
when you want to design a new antenna of the same general type.
Modeling Complex Structures
One project I undertook was the modeling of a group of towers, each of
which had a top hat. First, I constructed a fairly elaborate model of
a single tower. Next, I modeled a single, large diameter wire of the
same height, adjusting the diameter to obtain the same impedance as
the tower (the height needed only slight adjustment). This simpler
tower model was used for the remaining steps. A fairly elaborate top
hat model was placed on the simplified tower and analyzed. Then the
top hat was simplified as much as possible while retaining
approximately the correct impedance at the tower feedpoint (a good
example of the usefulness of ELNEC's Delete Wires function). Finally,
the group of towers was modeled, using the simplified models. This
approach can be taken for a variety of complex structures.
WHY NOT DBD?
It makes sense to compare an antenna's gain with the gain of a known,
real antenna. After all, the "isotropic radiator" doesn't exist. A
dipole is a common and convenient reference. So why not use the gain
of a dipole as a reference? When a dipole is used as a reference, the
gain is measured in "dBd", or decibels gain relative to a dipole.
(Similarly, the universally accepted standard "dBi" is decibels gain
relative to an isotropic source -- one which truly radiates equally
[poorly] in all directions). To use either term, a reference field
must be established. That is, we need to know the field strength that
an isotropic source or dipole would produce for the same power input
as the antenna we're comparing. The isotropic antenna has the great
advantage of being theoretical -- since it doesn't exist anyway, we
can precisely define its field strength under theoretical conditions.
This makes it constant and not subject to ground, orientation, or any
real considerations. But what's the gain of a dipole? Well, the gain
of an infinitely thin, half-wavelength dipole in free space is 2.15
dBi. But that's no more "real" an antenna than the isotropic radiator!
The danger in using 2.15 dBi as 0 "dBd" is that it's easy to get the
34
impression that it represents the gain of A REAL DIPOLE. It does not!
To see just how bad an error this represents, model YOUR reference
antenna using ELNEC and see what the gain actually is. The gain of the
"back yard dipole" modeled in TEST DRIVE has a gain of 6.8 dBi (or
+4.65 "dBd") -- just by putting the dipole in the back yard, we've
picked up more than 4 dB gain "relative to a dipole"! (One of the
factors increasing the gain of a dipole over ground is that all its
power is concentrated in one hemisphere -- above ground -- while the
isotropic radiator and free-space dipole spread power over both.) For
these reasons, ELNEC uses the universally accepted and unambiguous
standard: dBi. ELNEC permits you to enter any other reference of your
choosing, but it's highly recommended that you use it for comparison
between models of REAL antennas. Decide what reference antenna to use
and model it. Find the gain at the elevation and azimuth angles of
interest (Who cares what the maximum gain of an antenna is if the
maximum is straight up?) and use that as a reference to compare other
antennas against.
35
E L N E C
R U N N I N G E L N E C
36
STARTING ELNEC
Make the ELNEC subdirectory the current directory by typing 'CD
ELNEC'. If you have a Hercules graphics system, type 'MSHERC'
(followed by a carriage return). Type 'ELNEC' to start the program.
It is possible to start ELNEC from a different directory than the one
containing ELNEC.EXE. However, attention must be paid to the location
of certain files, so this isn't recommended unless you're willing to
give the necessary attention to the file location. Note that "current
directory" means the directory you were in when you started ELNEC; not
necessarily the directory containing ELNEC.EXE. ELNEC looks for the
configuration file ELNEC.CFG in the current directory. Also, ENSETUP
saves ELNEC.CFG in the current directory. So you should always run
ENSETUP and ELNEC from the same directory. If you are using MaxP,
MAXP.EXE also must be in the current directory, and EN.BAT must be
modified (see the MaxP manual). These are the only restrictions which
apply.
STARTING ELNEC IN TRACEVIEW MODE
If you've saved traces (pattern plots) and want to take another look
at them, print them, or compare them without doing a new far-field
calculation, you can use the TraceView mode. This is done by typing
'ELNEC TV' at the DOS prompt. More information about TraceView is in
the REFERENCE MANUAL chapter, p. 46.
TEST DRIVE
The best way to get familiar with ELNEC is to take it for a spin.
Let's analyze a 20-meter dipole hung 30 feet up in the back yard. If
you've started ELNEC, you should see the Main Menu. The file
DIPOLE1.EN is included on the disk and should be installed at the
proper location, so let's start with that antenna and modify it as
necessary.
(Note: <RET> means carriage return or Enter, <ESC> is the Escape key.
You may type any entry in uppercase, lowercase, or any combination.)
Type all characters inside the single quotes ('') but not the quote
marks themselves.
37
--------- Along the Straightaway ----------
From the Main Menu, type 'RE'. You don't have to follow it with <RET>.
You should see a list of all the antenna files in the default
directory (there should be several). DIPOLE1.EN should be on the list.
If not, the antenna (.EN) files are not installed where ELNEC can find
them (ELNEC is looking for them in the directory named near the top of
the screen). See INSTALLATION, p. 13, and RUNNING ENSETUP, P. 13, if
DIPOLE1 doesn't appear. Assuming DIPOLE1 is on the list,
Type 'DIPOLE1' <RET>
The TITLE shown near the top of the Main Menu should now read "Dipole
in free space" -- this is the title of the antenna description stored
in file DIPOLE1. Let's enter a title for our back yard dipole. As you
type, notice the cursor near the lower right corner of the screen. The
first letter you type will appear in this area. When you type the
second, ELNEC will begin the desired action, terminate the entry, and
erase both letters. If you type an unrecognized combination, the
program will ignore and erase them so you can start over.
Type 'TI'
This brings up an entry area near the bottom of the screen.
Type 'Back yard dipole' <RET>
Now the new title is entered and appears near the top of the menu.
Let's change the frequency to twenty meters --
Type 'FR', then '14' <RET>
You've now entered 14 MHz as the frequency. Let's choose feet for a
convenient unit of measure.
Type 'UN', then 'F'
to select feet. Presuming you don't have a perfect ground plane in
your back yard (and for many wavelengths in all directions), you'll
want to do the analysis over "real" ground.
Type 'GT', then 'R'
At this point you'll get a warning that the antenna is lying on or in
the ground plane. This sort of warning is typical of ELNEC; they
38
usually tell you quite specifically what the problem is. As you'll see
in a moment, the dipole we're starting with has z-coordinates of zero.
This is fine for free space, but isn't ok now that we've specified a
ground plane since the ground plane is at z = 0.
Press any key
to clear the error message and return to the Main Menu. (ELNEC returns
you to the Main Menu in case you want to solve the problem by changing
the ground type. In this case, you don't.)
Now we're ready to describe the antenna itself.
Type 'WI'
which takes us to the Wires Menu. Since we're starting from a dipole
description, the menu already shows one wire. We'll modify it to suit
our circumstances.
Type '1'
Note the highlighted area which appeared at the wire 1, end 1
coordinate area, and the prompt just below the wire description.
Assuming our back yard dipole was designed using 468/f(MHz) to
determine the length, the length is 33.43 feet. ELNEC doesn't require
any symmetry, so for convenience we'll put one end of the wire at x,y
= 0,0 and the other at x,y = 0,33.43. Placing it along the y axis
makes the maximum lobes at zero and 180 degrees, in the direction of
the x axis. Ground is always defined as being at z = 0 (for the
innermost medium). Since the antenna is horizontal and up 30 feet, the
z coordinate of both ends is 30. To enter the coordinates,
Type '0,0,30', then press the right cursor arrow ->
Pressing the arrow enters the value and moves the highlighted area, as
in spreadsheet entry. Separate <RET> and -> keystrokes also could be
used.
Type '0,33.43,30', then press the right cursor arrow ->
Both end coordinates are now entered. The next prompt is for wire
diameter (in inches or wire gauge). Supposing that the antenna is made
from #12 wire, just
Type '#12' <RET>
39
and the correct diameter is entered into the program. We could have
entered the diameter in inches if desired. The last item on the line
is the number of segments. 10 is a reasonable number for pattern
analysis of a half-wave antenna, so we don't need to change it.
Type <ESC>
to leave the wire description area. Before we leave the Wires Menu,
let's see what the antenna looks like
Type 'V'
and the screen changes to show a three-dimensional display of the
antenna. When finished viewing the antenna,
Type <ESC>
to exit the View Antenna screen and return to the Wires Menu.
Type <ESC>
to leave the Wires Menu and return to the Main Menu. Now let's put a
source at the center of the dipole.
Type 'SO'
and note that we've gone to the Sources Menu. The specified and actual
positions of source 1 are on wire 1, 50% of the way from end 1. This
is where we want it. The amplitude, phase, and type of source won't
have any effect on a single-source antenna (as long as the amplitude
isn't zero), so there's no need to change them.
Type <ESC>
to return to the Main Menu. Menu selection LO says that no loads are
specified. Since our dipole doesn't have any networks inserted in it,
zero loads is what we want. Now let's look at the ground description.
Type 'GD'
and note that we've gone to the Media Menu. One medium is shown, with
values corresponding to average soil. Suppose that our soil is very
good.
Type '1', then 'VG', <RET>
40
and note that the conductivity and dielectric constant have been
changed to appropriate values for very good ground. To end the entry
and leave the menu,
Type <ESC>, <ESC>
We know that the dipole's maximum lobe will be at zero degrees, but at
what angle above the horizon will it be maximum? We'll run an
elevation plot to find out. Selection PT shows that an azimuth plot is
the current choice, so
Type 'PT'
Note that the plot type has changed to Elevation. The azimuth angle
for the plot is zero degrees, which is where we'd like to look, and
all the other parameters look fine. To plot the pattern,
Type <RET>
When the plot is finished, note the choices in the upper right corner
of the screen.
Type 'A'
to run an analysis of the plot. The values appear on the screen, and
you can see the points on the pattern which ANALYZE found. This
assures you that ANALYZE is measuring what you think it's measuring.
If desired, you can print the annotated plot at this point by typing
'P'. This concludes the drive down the straightaway. If you'd like to
try your hand at a little more complex maneuvering, try taking
ELNEC. . .
---------- Through the Curves ----------
If you haven't yet done so, take ELNEC "along the straightaway" above.
In this section you'll begin with the plot generated by the
"straightaway" drive and get introduced to a few of ELNEC's more
advanced features. Several shortcuts are used in this section.
Remember that they don't have to be used -- when you're using the
program you can ignore them until you're more familiar with ordinary
entry methods. And when you are ready to use them, there's usually a
prompt on the screen to remind you how. Ready to go? Let's see how an
inverted vee compares with our back yard dipole. First we'll save the
dipole trace for future reference. With the "straightaway" plot on the
screen,
41
Type 'S'
to save the trace. Enter a file name for the saved trace:
Type 'BYDIPOLE' <RET>
then
Press any key
to return to the Main Menu.
Type 'WI'
to go to the Wires Menu. An inverted vee can't be made from just one
wire since it's bent in the middle and all wires must be straight. So
we'll have to add another wire and use each of the two wires for half
of the inverted vee.
Type 'A', then '1', <RET>
to add a wire. Then
Type '1'
to select wire 1. Let's put the center of the antenna at 0,0,30 (30
feet straight up from the origin). Note that end 1 of wire 1 is
already at this point, so
Press the right cursor arrow ->
to move to the other end of the wire. At this point, with other
modeling programs you would have to do some trigonometry or carefully
draw the inverted vee on graph paper to determine the coordinates of
the end. But not with ELNEC. We'll start with a dipole and use ELNEC's
Rotate feature to make it into an inverted vee. To make the inverted
vee the same length as the back yard dipole, each wire needs to be
16.715 feet long. So
Type ',16.715,' (note the two commas), then press the right cursor
arrow ->.
Since the x and z coordinates were already what we wanted, we can use
an entry shortcut. You only have to enter the coordinate(s) you want
to change, as you just did. The coordinates of end 2 of wire 1 should
42
now be 0,16.715,30. Since the wires are half as long as before, half
the number of segments should be adequate, so
Press the right cursor arrow -> again, then Type '5'.
Press the right cursor arrow ->, then the down cursor arrow
to highlight end 1 of wire 2. Here's another entry shortcut: To
connect this end to end 1 of wire 1,
Type 'W1E1', then press the right cursor arrow ->
and note that the coordinates of wire 1 end 1 have been duplicated for
wire 2 end 1, and that the end 1 Conn column shows the connection. For
wire 2 end 2
Type ',-16.715,30' (don't forget the comma).
Press the right cursor arrow -> twice, then Type '5', <RET>
to select 5 segments for wire 2. ELNEC automatically makes the
diameter of added wires the same as that of the wire just before the
new ones, so this doesn't have to be changed. Let's take a look at our
antenna so far.
Type <ESC>, then 'V'
to view the antenna. It should look like a straight wire.
Type <ESC>
to return to the Wires Menu. Now let's bend the wires down. The Rotate
and Length change features follow the rule that only the selected end
of the wire changes -- the other end stays put. Since we want the
center of the antenna to stay put, this means we need to operate on
end 2 of both wires.
Type '1', then press the right cursor arrow ->
to highlight end 2 of wire 1. Then
Type 'RE-45', <RET>.
This tells ELNEC to Rotate the wire 45 degrees in Elevation; the minus
sign means downward. Note the changed end 2 coordinates. To see what
happened,
43
Type <ESC>, then 'V'
to view the antenna. You can see that the wire has been bent downward.
Return to the Wires Menu and bend the other one down:
Type <ESC>, then Type '2', press the right cursor arrow ->, then
Type 'RE-45', <RET>
to rotate the other wire downward. Let's take a look:
Type <ESC>, then 'V'.
You should see an inverted vee.
Type <ESC>, <ESC>
to return to the Main Menu. Remember that we had one source in the
center of wire 1 for our dipole. We need to move it to end 1 of wire 1
or wire 2 to put it in the center of the inverted vee.
Type 'SO', '1', '1,0', <RET>
to put the source at end 1 of wire 1. You also could have specified
'2,0' for 0% from end 1 of wire 2. Or you could have entered 'W1E1'
just like you do for wire end connections -- ELNEC will recognize that
format, too.
Type <ESC>, <ESC>
to return to the Main Menu, then
Type <RET>
to generate the plot. When the plot is finished, notice that the gain
is a bit lower than for the dipole. But how do the patterns compare?
To find out,
Type 'R', then 'BYDIPOLE', <RET>
to recall the dipole trace and superimpose it on the inverted vee.
Note that when automatic outer ring scaling is selected, it's scaled
for the largest of all the plots being displayed. It can be shown that
the center of current for a sinusoidal distribution is 1/3 of the way
from the current loop. This means that the effective radiation
strength from the inner 1/3 of the inverted vee equals that from the
outer 2/3 (since the current is heavier toward the center). If we
44
raise the inverted vee by 3.94 feet, it will place this current center
at 30 feet, which was the height of the dipole's center of current.
Let's try it and see what happens:
Press any key, then Type 'WI'
to return to the Main Menu and go to the Wires Menu. To raise the
antenna 3.94 feet, just
Type 'H' then '3.94', <RET>
and all z coordinates are increased by 3.94 feet.
Type <ESC>, <RET>
to return to the Main Menu and generate the new plot. When the plot is
finished, it can be compared with the dipole trace:
Type 'R', then 'BYDIPOLE', <RET>.
The higher inverted vee is closer to the dipole pattern but still has
slightly lower gain. This shouldn't be surprising if you investigate
the patterns in more detail. The inverted vee has more radiation off
the end, reducing the gain from the side. But as you can see, the gain
difference between the dipole and inverted vee is only an
insignificant 0.5 dB (providing the centers of current are at the same
height).
Now you've taken ELNEC for a good run. Go ahead and begin
experimenting with your own antenna creations. The REFERENCE MANUAL
chapter, next page, contains complete information about each menu and
its features.
45
E L N E C
R E F E R E N C E M A N U A L
46
GENERAL INFORMATION AND CONVENTIONS
No distinction is made between uppercase and lowercase letters.
Scientific notation may be used for any numerical input if desired
(e.g., '7.15E6' = 7,150,000; '4E-3' = 0.004; '.123E2' = 12.3).
Because of size restrictions, a limited number of significant digits
can be shown in some menus. If fewer significant digits show than you
had entered, the program is still using the full-precision number (up
to seven significant digits) for calculations; the shortening only
affects the display.
Pressing <RET> (Enter) isn't necessary following entries requiring a
single keystroke. When the number of wires, sources, loads, or media
exceeds 9, the program requires a carriage return following entry of
the number; if the total number is 9 or fewer, it doesn't. Keystrokes
made while ELNEC is busy printing, calculating, or plotting are not
remembered. This is intentional to prevent you from having, say, a
plot which disappears as soon as it's complete due to an accidental
keystroke entered during the calculating/plotting process.
In the Wires, Sources, Loads, and Media Menus, the item highlighted
can be changed by using the arrow cursor keys and the PgUp and PgDn
keys. If the number of items exceeds the number which can be shown on
screen at one time, these same keys scroll the display. After entering
the desired value, the entry can be terminated using any of the above
keys or the carriage return. <ESC> also will terminate the entry but
the value you entered won't be saved.
During the impedance and current calculations, text and a graph are
shown which give the approximate percentage complete and time
remaining. These are only approximations, intended to give you a rough
idea of the time required to perform the calculations. The erratic
impedance calculation speed is normal, as ELNEC calculates some values
but recognizes others as being identical to previously calculated
points and skips them.
47
It's helpful to envision the antenna as you see it in the elevation
plots: the +x axis is to the right, the +y axis is into the screen,
and the +z axis is up. Use the View Antenna feature and look at some
of the example antennas and patterns to help you become familiar with
the coordinate system.
+z +y (into the screen)
| /
| /
| /
| /
| /
-x _____________|/_____________ +x
In azimuth plots you're viewing from the top of the antenna, so +x is
to the right, +y is up, and +z is out of the screen.
Azimuth angles are measured in the conventional mathematical sense --
counterclockwise from the +x axis: the +x axis is zero degrees, the +y
axis 90 degrees azimuth. Elevation angles are measured upward from the
horizon: the +x axis is zero degrees, the +z axis 90 degrees
elevation.
In general, the largest numbers permitted are about +/- 1E37, and the
smallest non-zero values +/- 1E-37. If the value being requested is an
integer (for example, the number of wire segments), the largest values
are about +/- 32,000. Because these values greatly exceed any
normally-required input data, ELNEC doesn't routinely check to see if
numbers you enter are within these ranges. If they are not, the
program will crash.
THE MENUS
The Main Menu
The Main Menu is the gateway for all program operations. From it, you
can change the antenna description and how the plot is done, save or
recall antenna descriptions, or do any other program function. Note
the cursor near the lower right corner of the screen. The first letter
you type will be shown. The second letter will terminate the entry,
begin the desired action, and erase the letters in the corner. If you
type an unrecognized combination, the program will erase them so you
48
can start over. Following is a description of each selection and its
operation.
TI -- TITLE
The title can contain up to 30 characters and may be any combination
of letters, numbers, symbols, punctuation, and spaces. The title
appears at the top of printed outputs.
FR -- FREQUENCY
Frequency is entered in MHz. The corresponding wavelength in current
units is shown beside the frequency. If you enter '0', the frequency
will be set to 299.7925 MHz, the frequency at which the wavelength is
one meter. At this frequency, dimensions and coordinates entered in
meters will also be in wavelengths. If you change the frequency when
units are wavelengths, you can choose to have the antenna stay the
same physical size (and change size in wavelengths) by selecting 'm'
or to stay the same size in wavelengths (and change physical size) by
selecting 'w'. If the latter choice is made, all wavelength-
dimensioned items are changed: wire end coordinates, wire diameter if
not specified as wire gauge, media heights, media boundaries, and
radial wire diameter if not specified as wire gauge. This can be used
with some caution to scale an antenna for another frequency -- see
"Scaling", p. 33. The FREQUENCY column shows SWEEP when Frequency
Sweep is on.
WI -- WIRES
Making this selection will bring up the Wires Menu, described below.
SO -- SOURCES
Making this selection will bring up the Sources Menu, described below.
LO -- LOADS
Making this selection will bring up the Loads Menu, described below.
GT -- GND TYPE
Choose this to select perfect ground, real ground, or free space.
49
GD -- REAL GND DESCRIPTION
If real ground has been selected (GND TYPE, above), this selection
will bring up the Media Menu, described below. If the ground type is
perfect ground or free space, this selection won't appear.
WL -- WIRE LOSS
This selection permits you to model the effect of wire loss, a feature
first available with ELNEC. ELNEC automatically calculates the skin
effect loss at the chosen frequency and inserts it into the model. You
can choose the built-in resistivities of aluminum alloy or copper, or
enter the resistivity and relative permeability of any other material.
(Note: Pure aluminum is seldom encountered in antenna work, and the
resistivity of alloys varies considerably. The built-in value is for
6061-T6 alloy, commonly used for antennas.) If the antenna is made of
more than one material, choose the material of the smallest-diameter
conductors or those carrying the most current. With plated wires enter
the parameters of the outermost material. Wire loss can have a major
impact on the performance of small or short antennas. Always do an
analysis including wire loss if a lossless antenna has gain that seems
too good to be true (because it probably is!)
UN -- UNITS
You can choose feet, inches, meters, millimeters, or wavelengths as
the units of measurement. Note: When feet are chosen, wire and radial
diameter are in inches; when meters are chosen, wire and radial
diameter are in millimeters. When wavelengths are chosen, you can
choose another unit for diameters. Headings and prompts tell you this
fact but it's easy to overlook.
PT -- PLOT TYPE
Entering 'PT' will toggle between Elevation and Azimuth plots.
PA -- AZIMUTH or ELEVATION ANGLE
This chooses the angle for the plot. For example, to see what the
azimuth pattern of your array looks like at an angle 20 degrees above
the horizon, choose AZIMUTH with selection PT, and 20 for selection
PA. See "Patterns", p. 28, for a more detailed description of the
meaning of the plots. If you switch back and forth between Azimuth and
Elevation plots, the angle for each is remembered and recalled when
you return.
50
PR -- PLOT/TABLE RANGE
To choose a plot/table range of 360 degrees (azimuth plots) or 180
degrees (elevation plots), enter 'F' (for Full range) when prompted.
Or you can save some calculation time by restricting the angles to a
region of interest. Step size (selection SS) must always be positive
but you can obtain any portion of the plot desired by putting the
upper and lower limits in the correct order. For example (assuming
step size = 5), lower limit = 10 and upper limit = 190 will plot 10,
15, 20, . . .,185, 190 degrees. Lower limit = 190 and upper limit = 10
will plot 190, 195, 200,. . .355, 0, 5, 10 degrees.
SS -- STEP SIZE
This determines the spacing between points on the plot or table. Since
the far field (pattern) is calculated for each point, far field
calculation and plotting time will vary with step size. 5 degrees is a
recommended step size for general purpose plotting, with 2 degrees if
the pattern has sharp lobes. Step size must be positive.
OR -- OUTER RING OF PLOT
If you enter 'A' for automatic scaling, the dBi value of the outer
ring of the plot will be chosen automatically. The automatically-
chosen value will be either an integer or the value of the pattern
maximum, depending on choice OA in the Options Menu. The outer ring
value can be fixed at any other value of your choice if desired.
FI -- FIELD(S) TO PLOT
If the plot is too cluttered with total, horizontal polarization, and
vertical polarization traces, you can force it to plot the total field
only. In HF skip communications the polarization is randomized by the
ionosphere so the total pattern generally is of most interest for HF
antennas. However, you might be interested in looking at the
horizontal and vertical polarization patterns to appreciate the amount
of fading which can occur due to the changing polarization.
AR -- ANAL RES
The ANALYZE features can be done with greater precision than the plot
if desired. For example, if ANAL RES is set to 1 degree, the direction
of maximum gain, sidelobe angles, 3-dB points, etc., will be
determined within 1 degree even if the step size is larger. Making the
ANALYZE resolution smaller will slow ANALYZE calculation but not any
others. If ANAL RES is greater than the plot step size (selection SS),
51
ANALYZE calculations will be done at a resolution equal to the step
size. When in the TraceView mode, ANAL RES is fixed at the step size
and can't be changed.
RF -- REFERENCE
If zero is chosen all plots, tables, etc. will be in dBi. The
REFERENCE value is useful if you want to use some other standard of
comparison such as a reference antenna.
SZ -- SWR Z0
Source data includes SWR for each source. This is the SWR which would
appear if the source were connected to the antenna through a
transmission line of a specific impedance. SWR values for a line
impedance of 50 ohms is always given, along with a second impedance
you can choose with this selection. This is useful if you want to feed
an antenna with a line of other than 50 ohm impedance and want to know
the SWR which will result.
--------------------------------------
(BR)owse file
This selection allows you to view any ASCII text file. It's
particularly useful to view a Frequency Sweep output, or to look at
files containing other data saved to files such as currents, source
data, etc. See SAVING, RECALLING, AND DELETING FILES, p. 84, for
information about entering a file name. To keep the screen
uncluttered, no prompts are shown during file display. Use the up and
down arrow keys and <PgUp> and <PgDn> to scroll. <Home> or <CTRL>-
<Home> will take you to the beginning of the file; <End> or <CTRL>-
<End> to the end. Press <ESC> to exit.
(DE)lete, (RE)call, (SA)ve description
These are used to delete, recall, and save antenna descriptions. You
can specify any name and path/directory to save or recall the files.
(There are restrictions on the extension.) If not specified, ELNEC
will assume the directory specified by ENSETUP or the Options Menu,
and the extension ".EN". If desired, calculated arrays can be saved
and recalled along with the descriptions; see SAVING AND RECALLING
ANTENNA DESCRIPTIONS, p. 84.
52
(Freq S)weep
This brings up the Frequency Sweep menu, described beginning on p. 78.
<RET> = Plot
A carriage return (Enter) generates a far-field plot (pattern). If
your computer doesn't have a graphics adapter, the heading will read
"<RET> = Table" and the data will be presented in tabular form.
(AN)alyze
ANALYZE calculates and shows forward gain, angle of forward gain,
front/back or front/side ratio, beamwidth, 3-db beam angles, major
sidelobe level, major sidelobe angle, and front/sidelobe ratio. These
are presented in tabular form. ANALYZE cannot be done before a plot or
table has been done; if you try, a message will appear. ANALYZE also
can be run while the plot is on the screen by typing 'A' according to
the prompt at the upper right corner of the plot (see The Plot Menu,
p. 70). If this is done, ANALYZE results will appear with the plot,
along with lines on the plot which show you exactly what ANALYZE
found. ANALYZE regards the second-largest lobe to be the "sidelobe"
for calculation purposes. If the front/back ratio is unity (zero dB),
ANALYZE will calculate the gain at an angle of 90 degrees from the
maximum direction and report the front/side ratio instead. If
displaying analysis data to the screen, you can scroll the display
with the up and down arrow keys and <PgUp>, <PgDn>, <Home>, and <End>.
Press <Esc> to return to the Main Menu. For saving to a file, see
SAVING, RECALLING, AND DELETING FILES, p. 84.
(CU)rrents
Prints (to the screen, printer, or file) a list of currents at each
segment junction. This is useful to observe the current distribution
on an antenna and to check for problems with the description or those
caused by specifying too few segments (see INTERPRETING THE RESULTS,
p. 28). If displaying to the screen, you can scroll the display with
the up and down arrow keys and <PgUp>, <PgDn>, <Home>, and <End>.
Press <Esc> to return to the Main Menu. For saving to a file, see
SAVING, RECALLING, AND DELETING FILES, p. 84.
53
(Load D)ata
Prints (to the screen, printer, or file) the impedance, voltage,
current, and power consumption of each load. This can be very useful
and enlightening when analyzing trapped or loaded antennas (see
INTERPRETING THE RESULTS, p. 28). If displaying to the screen, you can
scroll the display with the up and down arrow keys and <PgUp>, <PgDn>,
<Home>, and <End>. Press <Esc> to return to the Main Menu. For saving
to a file, see SAVING, RECALLING, AND DELETING FILES, p. 84.
(OP)tions
Making this selection will bring up the Options Menu, described below.
(Print D)esc
Prints the antenna description on the printer. This is useful for
documenting results.
(Src D)ata
Prints (to the screen, printer, or file) a list of the voltage,
current, impedance, power, and SWR (relative to 50-ohm or user-defined
impedance systems) at each source. Sometimes you'll see a negative
resistance and power. This isn't a flaw in the program; it actually
happens. When an array element shows a negative resistance, it means
there's net power flowing from the element into the feed system rather
than the other way around. The element gets this power by means of
mutual coupling. See INTERPRETING THE RESULTS, p. 28. If displaying to
the screen, you can scroll the display with the up and down arrow keys
and <PgUp>, <PgDn>, <Home>, and <End>. Press <Esc> to return to the
Main Menu. For saving to a file, see SAVING, RECALLING, AND DELETING
FILES, p. 84.
(TA)ble
Prints (to the screen, printer, or file) the far-field pattern data in
tabular form. If displaying to the screen, you can scroll the display
with the up and down arrow keys and <PgUp>, <PgDn>, <Home>, and <End>.
Press <Esc> to return to the Main Menu. For saving to a file, see
SAVING, RECALLING, AND DELETING FILES, p. 84.
54
(View A)ntenna
Graphically shows you what the antenna looks like. In addition, the
currents, field-strength pattern, and other useful information can be
superimposed on the antenna diagram. This selection doesn't appear if
a graphics adapter isn't present. See "The View Antenna Display and
Menu", p. 71, to learn how to get the most from this important
display.
(EX)it program without saving desc
Normally, the current antenna description is saved in file LAST.EN
when the program is exited. If this selection is made, the antenna
description won't be saved but the program will be allowed to
terminate even if the current description is defective. This is
intended as a way of "bailing out" if you've made changes which
prevent a normal exit. See (QU)it, below.
(QU)it
This is the normal way of exiting ELNEC. When ELNEC is exited, the
current antenna description is saved in the LAST.EN file for use the
next time the program is run. To prevent a defective description from
being saved, ELNEC might require you to correct certain problems
before permitting the program to end. If this happens and you don't
want to correct the problems, use 'EX' to exit.
The Options Menu
The Options Menu is entered by making selection 'OP' at the Main Menu.
Choices in the Options Menu remain in effect until changed or until
you end ELNEC. If desired, the changes can be made permanent. The
choices are read from file ELNEC.CFG each time the program is started,
and the current choices are stored in ELNEC.CFG if you elect to make
them permanent.
AD -- ABBREV DESC UNDER PLOT
If "yes" is chosen, ELNEC will print an abbreviated antenna
description below the plot (on the printer, not on screen). ANALYZE
information is included if ANALYZE has been run.
55
EN -- .EN FILE PATH
This selection defines the drive and directory where antenna (.EN) and
trace (.ENT, .F(#)) files will be stored. Although you may specify
other drives and directories when saving, recalling, and deleting
files, the drive and directory shown here are the defaults used when
not otherwise specified. You may wish to organize your .EN/.ENT files
in several directories and use this selection to move from one to
another. Enter the complete path from the root directory.
MA -- MAX P TEMP FILES PATH
This selection appears only if the Maximum Pulse Option (MaxP) is
installed. It is used to choose the location of the MaxP temporary
files. See your MaxP manual for more information.
OF -- OUTPUT FILE PATH
This selection shows the default path for all data output files saved
by ELNEC. These include Currents, Source Data, Load Data, Pattern
Tables, Analysis Data, and Frequency Sweep Data.
MS -- MICROSMITH FILE PATH
This is the path for MicroSmith files saved during a frequency sweep.
Normally, you would specify the directory containing the MicroSmith
program. If you don't have MicroSmith, disregard this entry. See
MICROSMITH, p. 89, for more information about this program.
GC -- DEFAULT GND CONSTANTS
These are the conductivity and dielectric constant which will be
assigned to newly added media (for example, when you change from
perfect ground or free space to real ground). You probably will want
to assign the values of your local ground to this selection.
Representative values for common ground types are given under "The
Media Menu", below.
GS -- GRID STYLE
You can choose between the ARRL-style logarithmic-dB scale or a 40 dB
linear-dB scale for the far-field pattern plots.
56
LF -- LAST FILE
You can choose to save all calculated arrays along with the LAST file
each time you exit the program. The advantage is that if you've run
the program then ended it, the pattern and calculated arrays will be
available when you start the program again. The disadvantages are that
a substantial amount of disk space may be required to save the arrays
(depending on the complexity of the antenna) and it will slow down
program termination. "Save description only" is the recommended choice
for floppy disk based systems and ones with limited hard disk space.
OA -- OUTER RING AUTO
When automatic scaling of the plot outer ring is chosen, you can
choose to make it equal to the pattern maximum or the next larger
integer dB value. The former makes it easier to read values from the
plot relative to the pattern maximum; the latter makes it easier to
determine dBi values.
PQ -- PRINT QUAL
This selection appears only if you've specified a 24-pin printer with
ENSETUP. "Draft" causes plot prints with 8-pin quality. "High Res."
plot prints use all 24 pins for higher quality but take longer.
PS -- PLOT STYLE
You can choose between "standard" and "plain" style plots. The former
includes information about the plot (time, date, maximum gain, etc.)
and the latter doesn't.
TU -- TABLE UNITS
You can choose to have tabular pattern data presented in terms of dBi
(or dBref), V/m at 1 mile (1 kW ref), or V/m at 1 km (1 kW ref). When
either of the latter two is chosen, the antenna is assumed to have an
input power of 1 kW for determining table V/m values.
PC -- PARALLEL WIRE CORR
The Parallel Wire Correction is a correction to basic MININEC
mathematics. It should normally be on to permit ELNEC to correctly
model close-spaced wires without needing a large number of segments.
It also corrects for other problems occasionally encountered, such as
inaccuracies arising from a short segment connected to a long segment.
The option of turning it off is offered only in case you have need to
57
compare results with MININEC or earlier ELNEC versions, since the
correction may cause minor differences in results between this and
earlier ELNEC versions.
The Wires Menu
The Wires Menu is entered by making selection 'WI' at the Main Menu.
At the upper portion of the display is a summary of the wires:
connections, end coordinates, diameter, and number of segments. Wire
end coordinates are defined as x, y, z coordinates relative to the
origin (+z is up, the +x axis -- 0 degrees azimuth -- is to the right,
and the +y axis -- 90 degrees azimuth -- is into the screen). The
"Conn." column shows connections to other wires; if a wire end is
connected to more than one other wire, only one connection will show
in this column. Since defining the wires usually is the most time-
consuming part of describing the antenna, ELNEC includes several
shortcuts to make the task faster and easier. Remember that you don't
have to use the shortcuts -- they're there only for your convenience
if and when you want to use them. The apparent complexity of this menu
is mostly due to the number of shortcuts ELNEC provides.
Entering or changing wire coordinates
Note that wires are considered to be straight, extending from one end
coordinate to the other. If two wires have the same end coordinates
they're considered to be connected. If a ground is specified and a
wire end has a z coordinate of zero, the end is considered to be
connected to ground. Crossing wires does NOT connect them; they may be
connected only at the ends. If a ground is specified, wire ends may
not have a negative z coordinate and the ends both can't have zero z
coordinates.
To enter or change wire coordinates, simply type the wire number. This
will highlight end 1 of the selected wire. To move to end 2, press the
right cursor arrow key. Wire coordinates can be entered in two
different ways. Either may be used as desired:
1. Conventional. Just enter the x, y, and z coordinates when
prompted, separating them with commas. IF YOU NEED TO CHANGE ONLY
ONE OR TWO COORDINATES, IT'S NOT NECESSARY TO REENTER ALL THREE.
Simply leave unchanged coordinates blank. For example, to change
coordinates 3.75,4.95,.713 to 3.85,4.95,.713 you only need to type
'3.85,,'.
58
2. As connections to other wires. To connect a wire end to another
wire end, type 'W#E#' for "Wire number End number". For example, to
connect an end to wire 3, end 1, type 'W3E1' at the prompt for
coordinates. The correct coordinates will be entered and the
connection shown in the "Conn." column.
Once entered, the end coordinates can be modified in several ways.
When using the Length and Rotate features it's helpful to keep in mind
the following rule ELNEC uses: Only the coordinates of the selected
end will be changed; the other end won't change.
1. Changing the length. Once wire coordinates are entered, the
length can be changed as follows: Select the end to be changed,
then type 'L###' where "###" is the new wire length. The
coordinates of the selected end will change to make the wire the
new length, in the same direction as before. To illustrate its use,
consider an inverted vee antenna guyed to the corners of a lot from
a single tower. First create a long inverted vee extending from the
tower to the lot corners by entering the coordinates of the tower
top and lot corners for the wire ends. Then change the lengths of
the wires to their real values. This eliminates the tedious
trigonometric problem of figuring out what the actual antenna end
coordinates are. Alternatively, a change in length, rather than a
new length, can be specified by entering 'L+###' or 'L-###'. For
example, 'L-3.4' would shorten the wire by 3.4 units. This is a
powerful feature for studying things like the effect of changing
the length of drooping radials.
2. Rotating the wire. The wire can be rotated by entering 'RA###'
(Rotate Azimuth) or 'RE###' (Rotate Elevation) where "###" is the
desired amount of rotation in degrees. The rotation amount can be
positive or negative, with positive meaning counterclockwise
azimuth rotation or upward elevation rotation. The highlighted wire
end will move. The other end will be the center of rotation and
will stay put. When performing elevation rotation you won't be
permitted to rotate a wire closer than about 1 degree to vertical,
and you won't be able to rotate a vertical wire in elevation. This
is because ELNEC keeps the same azimuth direction for an elevation-
rotated wire, and it can't tell which direction to move a vertical
wire. There's no similar restriction on azimuth-rotated wires. The
rotation ability is a powerful feature for defining vee-type
antennas and delta loops. You can begin by defining a straight
antenna then rotating the wires to the desired angle. An inverted
vee example appears in TEST DRIVE in the RUNNING ELNEC chapter. A
process similar to the TEST DRIVE example can be used to make a
delta loop: Make a dipole with two wires, each 1/3 wavelength long
59
(use wavelengths for units if desired). Rotate the wire ends down
60 degrees, making an inverted vee as in the example. Then add a
third wire, specifying end connections to the ends of the "inverted
vee". Now want to adjust the height in feet? Just change the units
to feet, then adjust the height. No fuss, no muss, no trigonometry.
Entering or changing wire diameter
Note that the wire diameter might be in different units than the wire
end coordinates. Watch the heading of the "Dia" column and the prompt.
The diameter can be entered directly or as a wire gauge (AWG). To
enter it as a wire gauge, type '#--' where "--" is the gauge, at the
prompt. Wire gauges larger than #0 (e.g., #00) aren't permitted.
Entering or changing the number of segments
Entering the number of segments is simple; deciding how many to enter
can be more difficult. See the MODELING WITH ELNEC chapter, p. 20, for
more information. The total number of segments (approximately equal to
the total number of pulses) is shown at the bottom of the Segs column.
Connecting wires to each other
Wires can be connected only at their ends. Two ends are considered to
be connected whenever their coordinates are the same. Please note that
the Wires Menu shows coordinates only to three decimal points, so it
may appear that wires have identical coordinates when they actually
don't. You can verify wire connections by looking at the "Conn" column
of the Wires menu or by observing the wire connection markers in the
View Antenna display.
Connecting a wire to ground
If the ground type is Real or Perfect, a wire end is connected to
ground by specifying a z-coordinate of zero.
Adding wires
To add wires, choose 'A'. At the prompt, enter the number of wires you
want to add. They will be added after the presently defined wires. If
you want to add wires anywhere except at the end of the list, enter
two numbers separated by a comma. The first number is the number of
wires to add; the second is the wire number to place them after. To
place new wires at the very front of the list, enter '0' for the
second number. Don't worry about sources and loads; they'll stay on
60
the same wires they were on before, even if the wires change number.
Wires can also be added in the Group Edit mode (see below).
Deleting wires
Choose 'D' to delete wires. If you enter a single number at the
prompt, the wire with that number will be deleted. If you enter two
numbers separated by a comma, the two wires and all between will be
deleted. If there are any sources or loads on wires to be deleted,
ELNEC will notify you and ask for confirmation before making the
deletion. Sources and loads on other wires will stay on the same wires
they were on before, even if the wires change number. Wires can also
be deleted in the Group Edit mode (next section).
Group Edit
This feature allows adding, deleting, copying or moving groups of
wires, or entering a single value for the coordinates, diameter, or
number of segments of a group of wires. Since this feature is common
to several menus, it's explained following the sections on menus. See
GROUP EDIT, p. 82.
Renumbering a wire
Selection 'R' permits you to renumber a wire. This is most useful if
you desire to put a source on the lowest numbered wire in a group of
wires connected to a common point. See "Sources and loads at junctions
of more than two wires", p. 33, 53. Multiple wires can be renumbered
in the Group Edit mode (see above).
Changing antenna height
You can change the height of the entire antenna by selecting H. The
height of a group of wires can be changed by using the Group Edit mode
(see above).
Viewing the antenna
Type 'V' to see what the antenna looks like. This operates identically
to the 'VA' selection in the Main Menu except that you'll be required
to delete or modify any zero-length wires before viewing the antenna.
See The View Antenna Display and Menu, p. 71, for more information.
61
Changing units
Choice 'U' performs the same function as 'UN' in the Main Menu - it
permits changing the units of measure. This is particularly useful for
switching between wavelengths and other units, or for converting a
design from metric to English units or vice-versa. A second function
of this choice is to permit changing units without changing numbers,
described next.
Changing units without changing numbers
Selecting 'U', then preceding the units choice with '!', will change
the units without changing the numbers. This feature is included
because of a potential trap. You carefully enter all your antenna wire
end coordinates, then discover the units are meters, not feet like you
wanted. If you change the units, the units change but the wires stay
the same (incorrect) length as before. If you fall into this trap,
choose 'U' and select the new units, preceding the choice with '!'
(for example, '!f' for feet). The units will change but the numbers
you've entered for end coordinates and wire diameter will remain the
same. If changing from meters to feet, for example, a two-meter wire
will become a two-foot wire.
Preserve Connections
When Preserve Connections is on, moving a wire end will also move the
coordinates of all connected wire ends, so they stay connected to the
modified wire. It's a very useful feature in doing certain kinds of
antenna modifications, but results can be surprising and confusing if
Preserve Connections is on when thought to be off. Because of this,
the prompt blinks when the feature is on. When using Preserve
Connections, frequently use View Antenna to make sure your changes are
having the desired result.
Automated segment tapering
When wires intersect at an angle, particularly acute angles, a larger
number of segments is required for accurate results. Increasing the
number of segments the required amount may lead to undesirably slow
program execution or may cause you to exceed the maximum allowable
number of pulses. An alternative is to break the joining wires into
several one-segment wires of different lengths, short near the
junction and increasing as distance from the junction increases, to
achieve high accuracy with a moderate total number of segments. (See
TIPS, p. 31.) ELNEC provides an automated method of doing this
tapering. It's intended as an advanced feature for use in special
62
cases only after you're completely familiar with ELNEC. Note that the
tapering process permanently changes the antenna description so it's
very wise to save the description before you start. (ELNEC will ask
you if you want to do this before you begin.) When several wires are
to be tapered, you also may want to save intermediate descriptions in
case you make a mistake.
After typing 'T' and responding to the question about saving the
description, you're asked which wire to taper and at which end(s) to
put the short segments. Respond with the wire number and the end(s)
connected to other wires at an angle. If both ends are connected to
other wires at an angle (as, for example, in a delta loop), enter 'B'
(both) for the end number. ELNEC will then ask you for the minimum and
maximum permissible segment length. You can use the default values of
1/400 and 1/20 wavelength by pressing <RET>, or specify different
values. It will make the shortest segment equal to the minimum you
specify and will not exceed the maximum with any segment. The lengths
are in current units, or in wavelengths if you follow the number with
'w'. For example, '.002w,.02w' will taper lengths from .002 wavelength
to .02 wavelength. Don't forget to add the "w" if you intend to
specify in wavelengths. The program then will respond with the number
of wires and segments it will use to replace the wire. If this is ok,
press 'y' or <RET> and the wire will be replaced; if not, press 'n'
and you'll be able to specify new minimum and maximum segment lengths.
Doubling the minimum length will reduce the number of wires and
segments by one (per tapered end). The result of choosing a different
maximum will depend on several factors and may substantially change
the resulting number of segments. Adequate accuracy might result with
quite a large maximum segment size; you may want to experiment to
investigate this possibility.
The new wires will replace the old one. After you have tapered the
first wire, notice that some wires are brightened, and appear in color
on a color monitor. These are the new wires. If you want to taper the
next original wire, select 'T' again, and give the number of the first
non-brightened wire (which is the next original wire), followed by the
end(s) to have the short segment when tapered. If there are more total
wires than the screen can display at once, this wire will be the
bottom one on the screen. Continue the process until you have tapered
all the wires you wish to. The brightening/coloring of tapered wires
will persist until the antenna description is saved and recalled or
until ELNEC is exited and restarted.
Sources and loads which are at the end of a wire, or at the center of
a wire which is being tapered at both ends, automatically will be
moved to the correct locations on the new wires. Sources or loads at
63
other locations may not end up where desired. It would be a good idea
always to check the placement of all sources and loads after doing a
taper.
Wire Coordinate Errors
Wires must have a non-zero length. Also, if a ground plane (either
real or perfect) is specified, the wires can't lie on the ground plane
(zero z coordinates for both wire ends), or in the ground plane
(negative z coordinate). If any of these errors occurs, the affected
wires are shown as bright text and a description of the error appears
in the "Conn" column. Added wires are given end coordinates of 0,0,0
so they fall into this category. If you attempt to leave the Wires
Menu while zero-length wires are present, you'll get an error message
and be returned to the Wires Menu until the problem is corrected. The
error message includes a prompt which permits you to delete all zero-
length wires. You can choose to do this or return to the Wires Menu
and fix or delete the defective wires. If wires are in or on the
ground plane, an error message will appear. You'll be sent to the Main
Menu where you can correct the problem by specifying Free Space as the
ground type or by returning to the Wires Menu to raise the wires. You
won't be permitted to run or normally exit ELNEC with this problem
present.
The Sources Menu
To add or delete sources type 'A' or 'D'. To modify a source, type the
number of the source. Group editing functions also are available - see
GROUP EDIT, p. 82. Sources are placed in series with the specified
wire. Sources can't be placed at an open wire end. No more than one
source may be placed at a given position on a wire. At least one non-
zero source always must be specified.
Specifying the source position
With MININEC, this can be the most tedious part of the antenna
description. Here's how easy it is with ELNEC: If you want to put a
source at the middle of wire # 1, enter '1,50' at the prompt (for
"Wire 1, 50% of the way from end 1"). That's it. The source will stay
there, even if you add or delete wires, or change lengths or numbers
of segments. (Possible exception: it might move slightly to stay on
the "pulse" closest to the specified position. This is explained
next.) ELNEC does, however, require that sources be placed on
"pulses" -- junctions between segments. So when you specify a
position, ELNEC will place it at the nearest pulse and tell you where
64
its actual position is. The specified position is saved, and each time
a change is made to the wires the source is moved as close as possible
to that position. Both the actual and specified positions are shown in
the menu. If you want to place a source at a particular pulse number,
enter 'p#' where # is the desired pulse number. This was included in
case you want to duplicate MININEC descriptions with ELNEC. However,
it's NOT RECOMMENDED for general use since sources placed this way
will be treated just as MININEC treats them: they stay on the same
pulse number and may move from wire to wire or off all wires as the
antenna description is changed.
The source position also may be entered as 'w#e!' where # and ! are
the wire and end number, respectively, or 'w#c' to place at the center
of wire number #. For example, 'w5e2' will put the source at end 2 of
wire 5, 'w1c' at the center of wire 1.
Source amplitude and phase
There are no restrictions on amplitude or phase except that if a
single source is specified, it must have nonzero amplitude. If only
one source is specified, the amplitude and phase will have no effect
on the results (as long as the amplitude isn't zero).
Source type
ELNEC features both voltage and current sources. If only one source is
used the choice won't make any difference. For arrays driven with
multiple sources, the choice can make a significant difference in
array performance, and the choice should reflect the desired driving
conditions. Most phased arrays are designed to be driven with a
particular CURRENT ratio, so current sources should be chosen to
simulate a correctly-fed array (See THE ARRL ANTENNA BOOK, Fifteenth
or Sixteenth Edition, Chapter 8).
Adding and deleting sources
Addition and deletion are done the same as with wires. Refer to "The
Wires Menu", p. 58, for information.
65
Connecting a source to ground
Sources appear in series with the wire, so a grounded source is
specified by inserting the source at a grounded wire end. If you want
to place a source between ground and a wire end which isn't at zero
height, you'll first need to add a wire connecting the end to ground.
This is the same procedure you would have to follow to make the
connection to a real antenna.
Group Edit
See GROUP EDIT, p. 82.
The Loads Menu
Load placement, connection, addition, and deletion operates exactly
like corresponding source operations (with one exception, explained
below). Refer to "The Sources Menu", above, for information. Loads are
placed in series with the wire. The one difference between source and
load addition is that if no loads are specified, a single load can
simultaneously be added and selected by typing '1' from the Loads
Menu. This choice appears at the bottom of the screen when no loads
are specified.
Specifying or changing impedance
Impedances may be entered either as resistance and reactance (R + jX)
or as a quotient of Laplace transform polynomials of up to fifth
order. All loads must be entered as the same type; if the type is
changed, all existing loads will be deleted (after notifying you and
receiving confirmation). The type which is in effect is indicated by
the heading of the right-hand column or columns. The type is changed
by typing 'T' at the Loads Menu prompt.
Using Laplace transforms
The advantage of using Laplace-transformed load impedances is that the
impedances will be automatically adjusted as the frequency is changed.
Although a detailed discussion of the use of Laplace transforms is
much too complex for this document, ELNEC will "translate" simple
series and parallel RLC circuits for you as explained below.
When the Laplace entry type is in effect, the heading will indicate
this fact, and "Select to show values" will appear in place of the
load impedances. When the highlighted box is moved to that area,
66
another menu will appear near the bottom of the screen, permitting
entry of the s coefficients. At least one denominator coefficient must
be nonzero. To select other loads while in the Laplace transform
submenu, use the PgUp and PgDn keys. Press <ESC> to return to the
Loads Menu.
At the prompt "Coefficient, 'S', or 'P'", enter the coefficient for
the highlighted area, the letter 'S' (for series RLC circuit), or 'P'
for parallel RLC. If you type 'S' or 'P' you'll get another prompt,
for the values of R in ohms, L in henrys, and C in farads. Three
values must be entered in the order R,L,C, separated by commas. Enter
0 to indicate a missing component. For example, a series or parallel
combination of 200 pF and 3 uH would be entered as '0,3E-6,200E-12'.
(Note the entry order: R first, then L, then C. In this example, R is
missing so is entered as 0.) The corresponding Laplace coefficients
will be entered for you.
Group Edit
See GROUP EDIT, p. 82.
The Media Menu
This menu is available when "real" ground is selected. The ground
model can consist of any number of "media". These media are shaped as
concentric rings or parallel "slices". If concentric rings are chosen
(radial boundary), the innermost ring is at z coordinate (height) of
zero and is centered at the origin. If "slices" (linear boundary) are
chosen, the boundaries are straight and parallel to the y axis. The
first medium boundary is at x = 0. If radial boundaries are chosen,
radial wires can be inserted in the innermost medium. Their length
extends to the outer edge of the innermost medium. The media may be
placed at various heights to simulate sloping ground if desired. NOTE:
The ground description affects only the far-field pattern. When
currents and impedances are calculated, a perfect ground approximation
is used. Therefore, the impedance of grounded vertical and low
horizontal antennas won't be accurate. This is a limitation of the
basic MININEC computational code.
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Entering the conductivity and dielectric constant
The conductivity and dielectric constant of the ground vary with the
type and dampness of the soil. Typical values for several types of
soil, as well as a map of typical average soil conductivities for the
U.S., are given on page 3-3 of THE ARRL ANTENNA BOOK, 15th or 16th Ed.
(ARRL) and in other handbooks. Values from THE ARRL ANTENNA BOOK for
some common ground types are:
Ground Type Quality Conductivity Diel.Const.
(Siemens/m)
Fresh water .001 80
Salt water 5 81
Pastoral, rich soil very good .0303 20
Pastoral, heavy clay soil average .005 13
Rocky, typ. mountainous poor .002 13
Cities, industrial areas very poor .001 5
Cities, hvy industrial extremely poor .001 3
As a shortcut, values for very good, average (good), poor, or very
poor soil can be entered by typing 'VG', 'A' or 'G', 'P', or 'VP' when
either the conductivity or dielectric constant is highlighted. When a
ground is first specified or when new media are added, values of
conductivity and dielectric constant are assigned according to the
DEFAULT GND CONSTANTS choice in the Options Menu. These values can be
changed at any time by entering the new value while the value to be
changed is highlighted.
Entering the R or X boundary coordinate
The boundary type can be determined by observing the heading of the
next-to-right-hand column: "R" indicates radial boundary and "X",
linear. This can be changed by selecting 'B' from the Media Menu when
no media are highlighted. The boundary coordinate is the coordinate
where the boundary begins; the last medium extends to infinity. THE
VALUE OF THE COORDINATE OF EACH MEDIUM SHOULD BE GREATER THAN THE
BOUNDARY OF THE PRECEDING MEDIUM. If it isn't, results may not be
accurate. This is one of the few places where ELNEC will permit you to
enter values which may lead to incorrect results. If a radial boundary
is chosen and radial wires are specified, the boundary of the second
medium (where the first medium ends and the second begins) is also the
end of the radial wires.
As an example, suppose you want to model a lake surrounded by a
"doughnut" of rich soil, which in turn is surrounded by average soil.
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Perhaps the lake is 2000 feet across. You'll have to model the lake as
perfectly circular, and three media must be specified to imitate the
lake and two ground conditions. The inner boundary of the first medium
(the lake) is defined to be at x,y,z coordinates 0,0,0. Make sure the
boundary is radial (see the above paragraph). Specify the conductivity
and dielectric constant of the first medium as .001 S/m and 80,
respectively, to model the fresh water of the lake. The inner boundary
of the second medium is the outer boundary of the lake, so specify
1000 feet for the second medium boundary. The conductivity and
dielectric constant for rich soil are about .03 S/m and 20, so specify
these for the second medium. Finally, the third medium has an inner
boundary which corresponds to the interface between the rich and
average soil, and conductivity and dielectric constant of .005 S/m and
13 to model average soil. The conductivity and dielectric constant of
the last (third) medium are presumed to exist outward from its inner
boundary. Place your antenna anywhere you wish relative to the lake;
it doesn't need to be at the center of the coordinate system.
Entering the medium height
There are no restrictions on medium height except that THE GROUND
UNDER THE ANTENNA ALWAYS SHOULD HAVE A HEIGHT OF ZERO for correct
results. ELNEC will not recognize any shielding effects from "hills",
"cliffs" or similar features. Like MININEC, it looks for a straight-
line path to a medium surface to determine the strength of the ray
reflected from that surface, and ignores features between the antenna
and the reflection point and beyond the reflection point.
Adding and deleting media
These functions are exactly the same as the corresponding functions in
the Wires Menu. See "The Wires Menu", p. 58, for details.
Changing the boundary type
Typing 'B' from the Media Menu toggles the boundary type between
radial and linear. The boundary type can be determined by observing
the next-to-left-hand column heading ("R Coord" for radial, "X Coord"
for linear).
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Adding or changing radials
Selecting 'R' brings up a small display near the bottom of the screen
showing the number of radials and the diameter of the radial wires.
The radials are considered to extend to the outer edge of the
innermost medium; if only one medium is specified, the radials are
infinite in length. Radials are used only to modify the ground
conductivity for far-field (pattern) calculation; they will have no
effect on ELNEC's indication of impedance or currents. THEY CANNOT BE
USED TO EVALUATE THE EFFICIENCY OF A GROUND SYSTEM. The calculation is
the same as that used by MININEC. THE MININEC CALCULATION METHOD IS
ACCURATE ONLY FOR A LARGE NUMBER OF RADIALS. The assumption is made
that the ground is homogeneous; that is, that the individual radial
wires are close enough together that their only effect is to modify
the conductivity of the ground within the circle in which the radials
are placed. Note that the wire diameter might be in different units
than coordinates and boundaries. If desired, the diameter may be
entered as wire gauge (AWG) by typing '#--' where "--" represents the
wire gauge. Gauges of wires larger than #0 (i.e., #00) are not
permitted. When you are finished with radial entry, press <ESC> to
return to the Media Menu.
Group Edit
See GROUP EDIT, p. 82.
The Plot Menu
This small menu appears in the upper right corner of the screen after
the plot is completed. Following are the selections and their effects.
(A)nalyze and annotate plot
This runs ANALYZE, and the results (gain, beamwidth, front/back or
front/side ratio, etc.) are shown on the plot along with lines
indicating the directions of maximum gain, 3-dB points, and sidelobe.
See Main Menu (AN)alyze, p. 33, 53, for more information. If multiple
traces are on the screen, only the "primary" trace is analyzed. In
normal operation, this is the one which was calculated. In TraceView,
it's the one selected from the Main Menu or at the start of the
program. If ANALYZE is selected following a frequency sweep, the last
pattern calculated (for the highest frequency) is analyzed.
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(P)rint screen
Prints the plot on the printer. If you've chosen to print an
abbreviated description under the plot (see "The Options Menu", p. 55)
and ANALYZE hasn't been run you'll get an additional prompt:
"(A)nalyze & incl on print". Typing 'A' at this prompt will cause
ANALYZE to run. The results will be included in the abbreviated
description below the plot but not on the plot.
Trace: C,D,S,R
Typing 'C' (Clear trace) will have an effect only if more than one
trace is on the screen. A list of recalled traces will appear and you
can choose to clear (remove) one or all of them.
'D' (Delete), 'S' (Save), and 'R' (Recall) operate on traces just like
the equivalent Main Menu selections do on antenna descriptions. Trace
files are saved in the same subdirectory as the antenna description
(.EN) files but are given the extension ".ENT". For compatibility with
earlier versions, files with any extension can be recalled or deleted.
However, files must have the extension ".ENT" to be saved. This
extension will be added by default if you don't specify one. See
SAVING, RECALLING, AND DELETING FILES, p. 84, for the use of "wild
cards" to list selected files. When traces are recalled, they are
automatically scaled to the current grid so that field strength values
read from the graph are accurate.
The View Antenna Display and Menu
The View Antenna display is a powerful feature that gives important
information about the antenna. The three-dimensional display of the
antenna is useful in verifying that the antenna has been described as
intended. Following is a brief description of other objects which are
or can be included on the screen along with the antenna display:
Coordinate system and origin marker
The display includes lines showing the directions of the x, y, and z
axes. A distinctive marker shows the position of the origin (x,y,z =
0,0,0 point). The axis lines are solid when the origin is at their
intersection. They are shown dashed when it isn't.
Source and load positions
Source and load positions are shown.
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Currents
Much valuable information about antenna operation can be determined by
observing the currents flowing on the wires. Current magnitude, and
optionally phase, are shown, with special indicators to aid in
interpreting phase. See INTERPRETING THE RESULTS, p. 28, to learn more
about taking full advantage of this important display.
Segment dots
Dots show wire segment junctions. These are useful in determining that
segments are of reasonable length and that segment lengths on
connected wires are similar in length.
Wire connection dots
Wire connections are shown with dots of different color and slightly
different size than the segment dots. These help show that wires are
connected as intended.
Unconnected wire end markers
When several wires join at a single point, one or more wires might not
be connected as intended due to errors in entering the antenna
description. The unconnected wire end markers show these by marking
all unconnected wire ends.
Far-field pattern
If the pattern has been calculated, it can be added to the View
Antenna display. This helps you see the relationship between the
pattern and antenna orientation. If desired, the pattern may be made
into a semi-solid figure for better visualization.
View Antenna operation: general information
The display can be rotated, positioned, and zoomed for easier viewing.
Additional zoom is available for the currents to facilitate analysis
of areas of low current. Wire identification is easily made using the
Highlight Wire feature. When enabled, this highlights the selected
wire and shows its end coordinates, connections to other wires,
diameter, length, and segment length. Colors of all objects can be
changed, and the changes kept temporarily or saved as new default
values. You'll find operation of the many features to be intuitive and
require little help from the manual. However, detailed information is
included below in the event it is required.
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The View Antenna display can be chosen from either the Main Menu
(selection 'VA') or the Wires Menu (selection 'V'). Operation is the
same in both cases. When first selected, you'll see the antenna,
coordinate axes, and other symbols, along with a menu. When first
viewed, the antenna will be scaled and placed on the screen so that
the coordinate system origin (X,Y,Z = 0,0,0) is at the intersection of
the axis lines. If the antenna is small and high, you may not be able
to see much detail. This is easily overcome, however, by using the
Center Ant or Zoom features. Any changes you make to the display will
remain until you recall a new description. When this is done, the new
antenna is scaled and placed on the display, and zoom and positioning
features are returned to their original states. Color changes remain,
however, until you reset them or end the program. You can make the
color choices permanent if desired, so that they are used each time
you start the program.
A note regarding the axis lines: When View Antenna is first chosen or
a new antenna description recalled, the intersection of the axis lines
is at the coordinate system origin (X,Y,Z = 0,0,0). However, the
antenna center or antenna shift features will move the axis lines
relative to the origin. (It's easy to be mislead by the fact that the
axis lines don't move on the screen when the origin moves away from
the axis lines.) Two aids are included to remind you of the origin
position. One is the origin marker which always remains at the
coordinate system origin. It may be off screen in some circumstances,
however. The other is that the axis lines are solid when their
intersection is at the origin, and dashed when not. Use these aids to
help keep track of the relationship among the antenna, the origin, and
the axis lines.
IMPORTANT NOTE: Although the View Antenna display will allow you to
change the size, position, and orientation of your view of the
antenna, there is no operation which will modify the antenna
description itself. That is, it is not possible to change the antenna
description in any way by using the View Antenna features.
Following is a detailed description of the features.
Arrow keys : Rotate
The arrow keys will rotate the display. This will help you get a
better idea of what the antenna looks like. If you rotate the antenna
to a confusing orientation, you can return to the default position by
pressing 'R'.
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<CTRL>-Arrow keys : Move
By holding down the <CTRL> key while you press an arrow key, you can
move the display on the screen. Rotation and zoom remain centered
around the intersection of the axis lines. The centered-antenna and
uncentered-antenna displays move independently. Pressing 'R' will
reset the centered-antenna or uncentered-antenna display (whichever is
being viewed) to its default position. IMPORTANT NOTE: The
combinations <CTRL>-up and <CTRL>-down don't work on XT-type
computers. If these combinations don't work, use <CTRL>-PgUp and
<CTRL>-PgDn instead.
+ - : Zoom
The antenna can be zoomed (magnified or reduced) by pressing the + or
- keys. The center of the zoom area is the intersection of the axis
lines. If you want to see more detail about a particular part of the
antenna, use the X, Y, Z and <CTRL>-X, Y, Z keys to move that part of
the antenna to the intersection of the axis lines, then use the zoom
feature ('+') to magnify. 'R' will restore zoom to its initial value.
NOTE to notebook computer users: You can use the "+/=" key with or
without <SHIFT> to magnify, and the "_/-" key to reduce.
<CTRL>+ - : Zoom currents
Pressing <CTRL> and + or - at the same time will zoom the currents
without affecting the rest of the display. This is useful in
magnifying areas of low current to see more detail. NOTE to notebook
computer users: The compiler used for ELNEC doesn't detect <CTRL> with
the "+/=" key, so provision has been made to make <ALT>-"+/=" and
<ALT>-"_-" zoom the currents also.
A : Reset all
This key resets both the centered and uncentered displays to their
original positions, magnifications, and colors. See R : Reset Position
to reset position and zoom only.
C : Center antenna image
'C' centers the antenna image around the axis line intersection and
rescales it. This is particularly useful to see more detail on, for
example, an antenna which is at a considerable height above ground.
Note, however, that ELNEC considers all wires in the description to be
part of the "antenna", so you still may not see much detail in, for
example, a Yagi-tower model. In that case you would have to use the
74
Zoom and Antenna Shift features to see more detail. The centered and
uncentered displays independently move and zoom but rotate together.
Unless no movement of the antenna image is required for centering, the
axis lines will become dashed when you press 'C' to indicate that
their intersection is no longer at the coordinate system origin.
H : Highlight wire
This feature is useful to identify a misplaced wire. It also gives
information about each wire. After pressing 'H', the menu will be
replaced by a display showing a wire number, and the coordinates, end
connections, diameter, length, and segment length of the wire. You can
select a wire either by using the up and down or right and left arrow
keys or by entering its number. As in the Wires Menu, it's not
necessary to press <ENTER> after entering the number if there are
fewer than ten wires. If you have an EGA or VGA monitor, the selected
wire will be a distinctive color which you can change if desired with
the 'O' selection in the View Antenna menu. Although highlighting
won't occur with CGA and some monochrome monitors, the numerical
information in this display can still be very useful.
I : Currents on/off
Pressing 'I' toggles the current display on and off. Current magnitude
is indicated by the distance of the line from the associated wire.
This display defaults to on when you start the program or recall a new
antenna description. Currents must be calculated by normal ELNEC
operation before they can be shown in the View Antenna display. If the
currents haven't been calculated, you'll briefly see a message to that
effect at the top of the screen.
<CTRL>-I : Current phase on/off
Current phase information is shown by pressing <CTRL> and 'I' at the
same time when the current display is present. Phase is indicated by
rotation of the current line around the wire. The best way to
interpret phase information is by turning on the phase indicators.
(See selection 0 (zero) below.) Phase information is useful in
determining that certain kinds of antennas are acting as expected. A
good example is the 4SQUARE example antenna. With the current phase
information on, you can readily see the phases of element currents. In
a long wire antenna, you can see the phase advance along the antenna
as indicated by the current line spiraling around the wire. In many
cases, however, the phase information will obscure what the current
magnitude is doing, so this feature defaults to off whenever you start
the program or recall a new description.
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0 (zero) : Phase ind on/off
If currents are being shown with phase information, this selection
turns special phase indicators on and off. These appear near the
center of each wire and consist of two lines, one solid and one
dashed. The solid line indicates the direction of zero phase and the
dashed line shows the direction of +90 degree phase. These are not
very useful when viewing an antenna which has had segment tapering
applied. In this case, each segment is a separate wire and has its own
phase marker, making the display hard to interpret.
M or F1 : Menu on/off
Either of these keys will turn the menu on and off. Turning the menu
off will give a wider viewing area and more uncluttered screen. When
the menu is off, no indication is shown on the screen about how to
turn the menu back on. Remember when you turn it off that the same key
will turn it back on.
O : Select colors
This selection isn't shown on the menu and isn't available if ELNEC
has detected a Hercules or CGA adapter, or you have indicated a
monochrome or LCD monitor with ENSETUP. Otherwise, pressing 'O' will
replace the normal menu with a color selection menu. Select the item
with the up and down arrow keys, and color with the left and right
arrow keys. The colors you have chosen will remain until you exit
ELNEC or press 'A' (Reset All). If you select 'M' (Make Permanent)
when the color menu is active, your color choices will be saved in the
ELNEC.CFG file and become the default colors.
P : Print
This key causes the display to be printed. You're asked to confirm the
choice so you can avoid printing if the key was accidentally pressed.
A "beep" indicates that ELNEC is finished sending the plot to the
printer and that you can resume normal operation.
R : Reset position
This resets the rotation, display shift, antenna shift, and zoom. If
you have chosen to center the antenna ('C'), the position of the
uncentered display won't be affected and vice-versa. Both centered and
uncentered displays will be rotated to the default orientation.
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S : Seg dots on/off
This turns on and off the dots which show the segment junctions
(pulses). Wire connection dots, which are distinctively colored and
larger in size, are turned on and off with the other segment junction
dots.
<CTRL>-S : Uncon ends on/off
Pressing <CTRL> and 'S' at the same time turns the unconnected end
markers on and off. These are most useful at spotting an unconnected
end in a group of wires connected to a common point. If one is
spotted, choose Highlight Wire ('H') and scroll through the wires
connected to the junction until you see one with no connection shown
to the end in question.
T : Pattern on/off
If the pattern has been calculated, 'T' turns on the display of the
far-field pattern (trace). Pressing it a second time makes the pattern
semi-solid, which particularly helps in interpreting azimuth plots
made at other than zero elevation angles. A third press of 'T' turns
the pattern display off. Please note that to speed rotation and other
movement, ELNEC doesn't attempt to always correctly show which line is
closest to the viewer. This may occasionally result in a display which
shows a seemingly impossible relationship between the images of the
antenna and the pattern, particularly when the pattern is semi-solid.
However, the primary purposes for presenting the pattern in this
display are to show the pattern shape and how it's oriented relative
to the antenna, and these always are correct. A pattern must have been
calculated by normal ELNEC operation before it can be shown on the
View Antenna display. If the pattern hasn't been calculated when you
press 'T', you'll briefly see a message to that effect.
X,Y,Z : Move ant image+
This feature will move the display of the antenna in the positive
direction along an axis. IT DOES NOT ALTER THE ANTENNA DESCRIPTION.
That is, the antenna is not actually being moved. (What is actually
happening is that the axis lines and center of the screen are being
moved relative to the antenna and coordinate system. The antenna is
staying fixed relative to the coordinate system, as shown by the
origin marker.) This feature is provided in the event that you want to
see more detail in some part of the antenna. To do so, use this
feature to move the portion of interest to the axis line intersection,
then use the Zoom feature to magnify it. (Zoom is always centered at
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the axis line intersection.) When you use this feature, note that the
axis lines become dashed to indicate when their intersection is no
longer at the coordinate system origin.
<CTRL>-X,Y,Z : Move ant image-
Pressing the <CTRL> key with 'X', 'Y', or 'Z' moves the antenna image
in the negative direction along an axis. See the preceding paragraph
for more information.
<ALT>-X,Y,Z : View from axis
Pressing <ALT> with 'X', 'Y', or 'Z' moves your viewing position to
the +X, +Y, or +Z axis.
<F2> - NoFlash on/off (VGA only)
When using a VGA display, View Antenna is shown with full VGA
resolution. Each time the display is changed, the screen must be
erased before redrawing the new view. This causes a "flashing" of the
display, which is particularly noticeable when the pattern is shown in
semi-solid form. (You may not notice this if you have a very fast
video card and bus.) The flashing can be eliminated by making use of
multiple screen "pages", a feature not readily available with VGA
resolution and the compiler used. Flashing can be eliminated at the
expense of lower EGA resolution by pressing <F2>. Pressing the key
again will return the display to VGA resolution. This has no effect on
the resolution of any other menu or display.
<ESC> - Exit Ant View
The <ESC> key returns you to the Main or Wires Menu.
Frequency Sweep and the Frequency Sweep Menu
ELNEC's frequency sweep capability can be a very valuable tool in
evaluating antenna performance over a range of frequencies. However,
operation is somewhat different in the frequency sweep mode, so it's
important to understand the operation in order to get the most from
this feature.
In non-frequency sweep operation, ELNEC calculates antenna impedances,
currents, and pattern, and keeps this information. When changes are
made to the antenna, only necessary recalculations are done. For
example, when a source is changed, only the currents and pattern are
78
recalculated. THIS IS NOT THE CASE WITH FREQUENCY SWEEP. It's not
possible to keep all the information for all frequencies, so
calculation results are written into a file after each frequency step.
Data present in arrays are erased and ELNEC is reset before beginning
calculations at the next frequency. Therefore, calculation results
from a frequency sweep are available only in the form of a file
containing the data. (In addition, a trace may be saved for each
frequency.)
Three outputs are available from the frequency sweep: far-field
patterns (traces), MicroSmith files, and data output. You can choose
to have ELNEC save any combination of these.
Far-field patterns (traces)
Far-field patterns are saved in the same form as traces saved from the
Plot Menu. However, they have the distinctive extensions .F1, .F2,
etc. to identify which frequency step generated them. They are shown
all together at the end of the frequency sweep, and can be recalled at
any time afterward in the same way as any other trace. They are saved
in the .EN file directory (declared in the Options Menu) unless you
specify otherwise.
MicroSmith files
MicroSmith is a program which enables you to see impedances on a Smith
chart display and to design networks to match antenna impedances. See
MICROSMITH, p. 89, for more information about this program. ELNEC
generates both .DAT and .GAM files for this program from the source #1
impedance data. Note that files are generated only for source #1. The
files are saved in a directory specified in the Options Menu. This
normally is the directory containing the MicroSmith program. Please
refer to your MicroSmith manual for the use of these files. MicroSmith
versions 2.000B and earlier were able to handle only eight frequency
steps in imported .DAT files, while later versions can handle many
more. ELNEC has the ability to set the maximum number of steps
recorded in the .DAT file to work with the version you have. See
RUNNING ENSETUP (p. 13) for information about setting this limit. The
.GAM file may be of use to some users who don't have MicroSmith. The
first line is the reference impedance. The remainder of the lines are
sets of frequency (MHz), reflection coefficient magnitude, and
reflection coefficient phase.
79
Data output file
The data output file contains any combination of the following which
you choose: tabular pattern data, source data (including SWR), load
data, currents, and pattern analysis. The combination you choose is
calculated at each frequency and written into the data output file.
This file is in ASCII format, and is formatted to be easily readable.
After the frequency sweep is finished, the file can be viewed by using
ELNEC's Browse feature ('BR' from the Main Menu) or by returning to
DOS and using other applications. It can be printed using the ordinary
DOS PRINT statement. This file is written into the output file
directory specified in the Options Menu.
Remember that if you decide later to add more items to the output,
you'll have to repeat the entire frequency sweep.
Using the menu
The Frequency Sweep Menu is accessed by pressing 'FS' when at the Main
Menu. All choices are reset when you recall a new antenna description
or end the program. Following is a detailed description of the choices
and what they do.
FO - FREQUENCY SWEEP
Turns frequency sweep on and off. Frequency sweep is turned on
automatically when you enter start, stop, and step frequencies.
FL - START, STOP, and STEP FREQUENCIES
The frequency sweep starts at the start frequency, ends at the stop
frequency, and the size of the frequency steps is the step frequency.
All these are entered at one time, separated by commas. For example,
to get data at 14, 14.1, 14.2, and 14.3 MHz, enter '14,14.3,.1' after
typing 'FL'.
PN - PAT PLOT FILE NAME
If you want to save far-field patterns (traces) for each of the
frequencies, type 'PN' and enter a file name. If, for example, the
file name is "TEST", ELNEC will save the trace for the first frequency
in file TEST.F1, the second in TEST.F2, etc. All traces will be shown
superimposed at the end of the frequency sweep run. If you have
already entered a name, a prompt will give you the opportunity, by
typing 'x', to delete the name. This doesn't delete the file - it just
deletes the 'PN' entry and disables saving of the pattern plots.
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SN - MICROSMITH FILE NAME
This entry works like 'PN', above. If you specify the name "TEST", for
example, ELNEC will create files TEST.DAT and TEST.GAM and place them
in the MicroSmith file directory specified in the Options Menu.
MicroSmith can use these files to display the impedance of source #1
on a Smith chart. Also, they provide the data MicroSmith needs to
provide the structure for you to design a matching network. Note that
only information about source #1 is contained in these files. To
obtain MicroSmith files for another source, you must renumber it as #1
and repeat the frequency sweep. The number of frequency steps which
will be written into the .DAT file may be limited. See "MicroSmith
files", p. 79. For more information about MicroSmith, see MICROSMITH,
p. 89.
FN - FREQ SWP FILE NAME
If no name is specified, no output data from the frequency sweep will
be saved (except patterns and MicroSmith files if selected). If you
want ELNEC to save tabular pattern data, source or load data,
currents, or pattern analysis, you must enter 'FN' and specify a file
name. None of this information will be available after the frequency
sweep unless it has been saved in the output file. After entering a
file name, select 'SF' to choose what data you want ELNEC to put into
the file. The frequency sweep output file can have any name
permissible by DOS and it will be placed in the output file directory
named in the Options Menu.
SF - SAVE IN FREQ SWP FILE
Type 'SF' to choose what data will be written by ELNEC into the data
output file named by choice 'FN' above. You will see a cursor to the
right of the choices. Pressing the space bar will make a check mark
appear at the cursor position. Pressing it again will remove the check
mark. Use the up and down arrow keys and space bar to put check marks
beside the items you want to save, then press <ESC> when finished.
Pattern table, source data, load data, currents, and pattern analysis
are the same data you see when you type 'TA', 'SD', 'LD', 'CU', and
'AN' from the Main Menu when not in Frequency Sweep mode. When you
first run a frequency sweep you might specify a run with only a few
frequencies and have ELNEC save all the items to get an idea of what
sorts of data they contain.
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(DE)lete freq sweep file
You can use this selection to delete a frequency sweep file or any
other file in the output file directory. You can also use it to delete
any other file by specifying the full path along with the file name.
(BR)owse freq sweep file
This works the same as the Browse function in the Main Menu. See the
Main Menu description, p. 48, for more information.
GROUP EDIT
The Group Edit feature may be used in the Wires, Sources, Loads, and
Media Menus. It permits adding, deleting, moving, or copying groups of
wires, sources, loads, or media. It also allows entering a common
value for one of the parameters for a group of wires, sources, loads,
or media. All special editing features, such as changing wire length
or rotating wires, are available in the Fill mode. A special feature
in the Wires Menu permits changing the X, Y, or Z coordinate of a
group of wires. Despite the lengthy explanation below, Group Edit is
easy to use by simply following the instructions given by the prompts.
A few minutes of experimentation will be very helpful in understanding
how the operations work. The Wires Menu will be used for the following
examples, but most operations except X, Y, and Z work the same way for
all menus. Special cases for various menus are described at the end of
this section. Note that shortcut add and delete functions are also
available from the menus without entering the Group Edit mode.
Starting Group Edit and selecting a group of items
Group Edit is started by selecting 'G'. After selecting, more choices
are shown at the bottom of the screen. Adding and deleting are self-
explanatory. Copying is useful in modeling stacked antennas, and for
making multiple copies of complex sources or loads. Moving groups
won't affect results but may be helpful in putting items in a more
logical order. The Fill choice permits you to fill a group of cells
(for example, the diameter of a group of wires) with the same value or
to perform the special editing features on a group of wires. (See
"Filling Cells", and "Special Notes: Wires Menu", below.)
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Adding: Entering how many
If you chose Add, you'll be asked how many to add, then will be asked
for a destination. Skip the next paragraph and go to the section on
selecting a destination.
Copying, Deleting, Filling, Moving: selecting a group
After choosing the action, you must next choose the range of wires
(for example) on which to operate. The range can be chosen in either
of two ways. You can either specify a range of wire numbers (such as
'3-5' or '3,5') or you can move the cursor to the starting wire
number, press '.' to "anchor" the choice (as in most spreadsheets),
then move the cursor to the last wire number. Finally, press <RET> to
finish the selection. For example, to choose the range 3-5, move the
cursor to wire 3, press '.', move the cursor to wire 5 (note that
wires 3-5 are now highlighted), and press <RET>. You can select all
wires by entering 'A'. If deleting wires, this completes the action
except for confirming that you want to delete. Skip the next step if
filling cells.
Adding, Copying, Moving: selecting a destination
What happens next depends on whether you initially selected Fill, or
some other action. If the selection was other than Fill, you'll be
asked for a destination. You can enter a single number, or move the
cursor until the box on the left is on the wire number FOLLOWING the
desired destination point and press <RET>. For example, to put copies
of wires 1-3 into the list following wire 5, select 1-3 for the group
as described in the previous paragraph. For the destination, enter '5'
followed by <RET>.
Filling cells
If you selected Fill, only one column will be highlighted, and you can
select the column with the arrow keys. As you position the highlighted
area in different columns, your choices will appear at the bottom of
the screen. These are the same choices you have when entering data in
the non-group mode. For example, to change the diameter of the
selected wires to one unit, move the highlighted area to the Dia
column, enter '1', then <RET>. When finished entering values, press
<ESC>. Note that in the Fill mode, all the powerful normal editing
features are available. For example, you can rotate or change the
lengths of all the selected wires at once. Or if you select a group of
wires and enter ',,15', the z coordinates of all the selected wires
will be changed to 15, but the other coordinates will remain the same.
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Special Notes: Wires Menu
The example at the end of the preceding paragraph shows how to change
the coordinate of a group of wire ends to a value you specify. Choices
X, Y, and Z allow you to change the coordinate BY a given amount.
After selecting the group of wires to change, one end of the group
will be highlighted. Select the wire end to change, then enter the
amount you want the X, Y, or Z coordinate to change. If you want to
reposition the wire, repeat on the other end.
If you move a group of wires, sources and loads on the wire will be
moved with them. If you delete a group of wires containing sources or
loads, you'll be warned that they'll be deleted before the action is
final. If you copy a group of wires which contain sources or loads,
you can choose to also make copies of the sources and loads at the
same positions on the new wires.
Special Notes: Sources Menu
Since no more than one source can be placed at the same place on a
wire, copies of sources will be assigned to "wire 0". You must assign
them to a legitimate wire before exiting the Sources Menu.
Special Notes: Media Menu
The boundary of each medium must be greater than the boundaries of the
preceding media. Therefore, ELNEC won't let you fill medium
boundaries. Also, the height and boundary of any medium becoming
medium number 1 are set to zero.
SAVING, RECALLING, AND DELETING FILES
When saving, recalling, or deleting a file, ELNEC will show you a list
of the appropriate files. The directory which is shown is determined
by the default paths you selected in the Options Menu. The path for
output files is the directory shown for Browse and data output
(currents, source data, load data, pattern table, analysis, and
frequency sweep) operations. The .EN path is the default for antenna
descriptions and far field patterns (traces). The path chosen for
frequency sweep MicroSmith file outputs is the default for MicroSmith
file operations. If the list is too long to fit on the screen at once,
you can scroll the display by using the up and down arrow keys and
<PgUp>, <PgDn>, <Home>, and <End>.
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A very convenient feature is the file list "wild card" capability.
"Wild cards" are the characters "*" and "?", which substitute for any
number of following characters and a single character, respectively.
If you specify a file name which includes a "wild card" character,
ELNEC will show all the files with that specification. For example,
'vert*' will show all files in the .EN file directory beginning with
"VERT" and having an ".EN" extension , e.g., VERT.EN, VERTICAL.EN,
VERT1.EN, etc. Specifying a "wild card" character when deleting files
will NOT delete all files with the given specification; they will only
be listed as described above. You can see what .EN files there are in
another directory, say \OLDANTS, by typing '\oldants\*' at the prompt.
If this is done, the specified directory will become the new assumed
path for any file name you enter.
SAVING AND RECALLING ANTENNA DESCRIPTIONS
See the section immediately above for additional information.
When you recall an antenna description, you are shown an alphabetized
list of the description files in the directory specified by ENSETUP.
If there are accompanying array files (explained below), a distinctive
solid-triangular mark is shown following the description file name.
To choose a description to save, recall, or delete, type its name at
the prompt. It's not necessary to type the path or directory for the
file names shown on the screen; the correct path will be added by
ELNEC. Also, the extension ".EN" will be added to antenna description
files and ".ENT" to trace files if you don't specify an extension.
Antenna description files must have an ".EN" extension and trace files
an ".ENT" extension to be saved. This can be manually entered or added
by ELNEC. For compatibility to earlier versions, you may recall or
delete files with any extension.
When you save an antenna description, ELNEC asks whether you also want
to save "calculated arrays". When ELNEC runs a far-field analysis, it
calculates several sets, or arrays, of values. The most important are
the impedance array, containing self and mutual impedances of all
pulses (segment junctions); the current array, containing the current
at each pulse; the voltage array, containing the voltage across each
segment junction; and the dB array, containing the field strength at
each specified azimuth or elevation angle. If you change, for example,
the azimuth or elevation angle for the plot, only the dB array needs
to be recalculated; if you change sources or loads, only the current,
voltage, and dB arrays need recalculation. ELNEC version 2 allows you
to save these arrays if desired so future calculations with the same
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antenna description won't unnecessarily have to be repeated. To do so,
simply type 'y' at the prompt asking whether you want to. (If no
arrays have been calculated, the prompt won't appear.) Before saving
the arrays, ELNEC checks available disk space and will refuse to save
them if there's not enough. The arrays are saved as files in the same
directory as the ".EN" (antenna description) files, as specified by
ENSETUP (see ELNEC FILES, p. 87). The largest files are the ones
containing the impedance arrays. There are two of these, and they can
be as large as 64k bytes each for a 127-pulse antenna. (Note: With
the Maximum Pulse Option, there can be several sets of these arrays,
with a total size of greater than 500,000 bytes.) The other arrays
are relatively small. If you specify that you don't want to save
arrays with an antenna description and arrays previously have been
saved with that description, THE EXISTING ARRAY FILES WILL BE DELETED.
TRACEVIEW
Starting TraceView
The TraceView mode is a way to look at, compare, or print saved traces
without having to run a far-field analysis. To use TraceView, start
ELNEC by typing 'ELNEC TV'. The program will begin by showing you the
saved trace files. You need to select one of these -- it will become
the "primary" trace. (The primary trace plays the same role as the
calculated trace in ELNEC's normal mode. ANALYZE is done on the
primary trace. The primary trace also determines the value of the plot
outer ring if automatic scaling is chosen, and an abbreviated
description under the printed plot will contain information on the
primary trace.) After you choose the primary trace, the Main Menu
will appear. Note, however, that most of the selections aren't
available. This is because ELNEC doesn't do any calculations or
antenna modifications in TraceView mode -- it's strictly for showing
existing traces. <RET> will plot the primary trace. You can print the
plot or recall additional traces just like you do in ELNEC's normal
mode.
ANALYZE and TraceView
If you wish, you also can ANALYZE the primary trace. Note, however,
that the analysis resolution is fixed at the plot step size. This is
because TraceView works only with the trace data and doesn't calculate
gain at points between those in the stored trace.
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Changing the Primary Trace
You can select a new primary trace by selecting 'RT' (Recall Trace)
from the Main Menu. This selection appears only in TraceView mode.
Ending TraceView
When you exit TraceView by selecting QU (QUit), the LAST file is NOT
altered.
ELNEC FILES
The only ELNEC files which are readable by using DOS commands TYPE or
PRINT, or utility viewer programs, are READ.ME, ANTNOTES.DOC,
ELNEC.DOC, and outputs which can be "printed" to a file (frequency
sweep output, and source, load, current, pattern analysis and pattern
table data). MicroSmith .DAT and .GAM files are ASCII format, but have
no explanatory information. All the others will appear as unreadable
ASCII characters.
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Files on the Distribution Disk(s)
If your ELNEC program came on two 360k disks, one disk is labeled
MANUALS and contains all files except ELNEC.EXE, and the other disk
contains only that file. Otherwise, all files are on the single 720k
or 1.2 Meg disk.
ELNEC.EXE and ENSETUP.EXE: These are the main program and the setup
program.
.EN (antenna) files: These files contain antenna descriptions, and
may be saved, recalled, and deleted from the Main Menu. Whenever you
save an antenna description, it is given the extension ".EN" and
stored in the subdirectory specified by ENSETUP or in the Options Menu
unless you specify otherwise when you save it. (If you don't specify a
directory, .EN files are saved in the current subdirectory.)
LAST.EN: This antenna file contains the description of the last
antenna analyzed. It's read when ELNEC is started, and the antenna
description present when ELNEC is quit is written into this file.
(Exception: If ELNEC is ended by selecting 'EX' from the Main Menu,
LAST.EN isn't changed.)
MSHERC.COM: This special driver must be loaded (run) before
starting ELNEC if your system has Hercules graphics. Once loaded, it
doesn't need to be reloaded until the computer is rebooted.
ELNEC.DOC: This file.
ANTNOTES.DOC: Contains notes about the furnished example antenna
description (.EN) files.
READ.ME: Contains brief instructions on how to print this file.
Files Created by ELNEC and/or ENSETUP
.GAM and .DAT files: These are files written in a special format
for use by the MicroSmith program. See the section on Frequency Sweep,
p. 78, for more information. They are written to a directory specified
in the Options Menu.
ELNEC.CFG: This file is created by ENSETUP or ELNEC the first time
either is run. It contains the printer type, path to the .EN files,
date format, screen colors, Options Menu choices, and View Antenna
colors. Each time ELNEC is run, it looks for this file in the current
directory, reads it, and uses the values it finds. If ELNEC.CFG isn't
found, ELNEC uses default values. ELNEC.CFG is modified by running
ENSETUP, choosing MP in the Options Menu, or M in the View Antenna
color selection menu. See RUNNING ENSETUP, p. 13, and "The Options
Menu", p. 55, for more information.
.ENT (trace) files: These files contain trace information and are
saved and recalled from the Plot Menu. They are stored in the same
subdirectory as the .EN files.
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.F(#) files: These are trace files created during a frequency
sweep. They have the same format as .ENT files. The file with
extension .F1 is the trace for the first frequency step, .F2 for the
second, etc. They can be recalled and viewed like the .ENT files. They
are stored in the same subdirectory as the .EN and .ENT files.
.ZR, .ZI, .V, .I, .DB files: These files contain arrays calculated
by ELNEC. They are created if you choose to save calculated arrays
with an antenna description or with the LAST file. They are stored in
the same subdirectory as the .EN files.
Data output files: Various outputs may be saved to a file. Also,
the frequency sweep data output always is saved to a file. These have
names specified by the user and are written to the data output
directory specified in the Options Menu.
If the Maximum Pulse Option (MaxP) is being used, additional temporary
files are created. See the MaxP manual for more information.
MICROSMITH
MicroSmith, by Wes Hayward, W7ZOI, is an inexpensive program which
allows you to view impedances on a Smith chart. With its aid,
impedance matching networks can be designed. ELNEC is able, in its
Frequency Sweep mode, to write files for direct input of source
impedance data to MicroSmith. MicroSmith is published by the American
Radio Relay League, 225 Main Street, Newington, CT 06111 USA, phone
(203) 666-1541. Contact them directly for price and ordering
information.
PRINTERS
Many of today's 8- or 9-pin dot-matrix printers can emulate an Epson
FX printer, and many 24-pin printers can emulate the Epson LQ series.
For laser printers, the HP LaserJet series has become a standard.
Drivers also are included for the Epson MX, which has a smaller set of
graphics density options, and for the HP DeskJet. The 8/9 pin IBM
Proprinter is compatible with the Epson MX for ELNEC graphics. The 24-
pin Proprinter also can use the Epson MX driver, but only 8-pin
resolution will be available. Even if your printer can't imitate any
of these exactly, it may respond correctly to the few necessary
commands and work satisfactorily. If you can't make plots print
correctly, and have tried the suggestions under PROBLEMS, your printer
isn't a compatible type.
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Note that the printer must be connected to the parallel printer port.
HPIB and serial buses aren't supported.
PLOTTERS
I've received a few requests for plotter drivers. ELNEC currently
creates a plot for the screen then "dumps" the screen data onto a
printer. This can't be done with a plotter. A plotter requires
creation of a separate, special plot just for its use. Because of the
relative complexity of the task and the limited demand, I don't plan
to provide plotter drivers for ELNEC.
PROBLEMS
Plot grid appears but no plotting apparently takes place:
You may be plotting the pattern in a direction in which the field
intensity is very low (< -50 dBi). Although nothing seems to be
happening, the program is calculating and plotting the far field but
the plot appears as a dot in the center of the grid. When calculation
is complete, the plot will expand and become visible (if outer ring
scaling is automatic), and the maximum gain will be shown to be very
low (frequently -99.99 dBi). The most common situation causing this
result is an azimuth plot at zero degrees elevation of a horizontal
antenna over ground, or a vertical antenna over real ground. (In both
these cases, the result of zero field strength is theoretically
correct. See p. 28, "INTERPRETING THE RESULTS", for more information.)
Gain is -99.99 dB and pattern is circular
See above problem.
ELNEC says it doesn't detect a graphics adapter:
If you have Hercules graphics, you must load (run) MSHERC before
running ELNEC. See the RUNNING ELNEC chapter, p. 36.
All the Frequency Sweep traces (pattern plots) are white on a color
monitor.
Run ENSETUP and select colors for recalled traces. Frequency Sweep
uses these same colors for the multiple-trace display.
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Plot is distorted on screen:
ELNEC is designed to automatically adjust for the resolution of your
graphics system type, and it assumes a standard 3:4 aspect ratio.
ELNEC presently contains no provision for changing the geometry of the
plot on screen. Distortion caused by the monitor can only be corrected
by adjusting or repairing the monitor. Distortion on the screen won't
cause distortion of the printed plot, however.
Printed plot is distorted:
The most likely cause is that you've specified the wrong type of
printer (8/9 pin instead of 24 or vice-versa). See RUNNING ENSETUP, p.
13. If changing the printer selection won't correct the problem, your
printer isn't a compatible type; see PRINTERS, p. 89.
Printed plot is negative:
Your printer isn't a compatible type; see PRINTERS, p. 89.
The program always starts with the "Default" antenna, or it shows
the "Default" antenna when a different one was recalled:
The program reverts to the Default when it can't find the LAST.EN file
or when a recalled file has been corrupted and ELNEC can't read it.
The first situation could happen if ELNEC.EXE has been moved since it
was last run, and can't find the path to the .EN files. If the second
situation occurs, the corrupted file is no longer usable and should be
erased.
Printed plot is garbled:
You may have specified a laser printer but are using a dot-matrix
printer, or vice-versa, or you've specified an FX-type printer and
your printer will recognize only MX graphics. See RUNNING ENSETUP, p.
13. Another possibility is that you have your printer set to emulate
an IBM Proprinter. This option, available on many printer types, is
typically selected with a DIP switch setting. If your printer is set
to this mode you must use the Epson MX driver. If none of these is the
case, the printer isn't a compatible type; see PRINTERS, p. 89.
A '%' sign appears in a menu entry:
This happens if the number of digits required to display the entry
exceeds the number of spaces allotted for it in the menu. It otherwise
has no affect on program operation.
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Changing ELNEC.CFG using ENSETUP doesn't have any effect:
Some changes to ELNEC.CFG won't have any effect on certain systems.
For example, since the plot is monochrome on CGA monitors, plot color
choices won't change plot colors on a CGA system.
ELNEC always looks in the current subdirectory for ELNEC.CFG.
Likewise, ENSETUP always modifies the ELNEC.CFG file in the directory
which is current when ENSETUP is running. You may be modifying one
ELNEC.CFG file and ELNEC is reading another. To make sure that ENSETUP
is modifying the correct file:
1. Make sure ELNEC.EXE and ENSETUP.EXE are in the same subdirectory
(hard disk systems) or on the same diskette (floppy drive systems).
The following step assumes that the subdirectory is \ELNEC.
2. Make sure that the subdirectory containing ELNEC.EXE and
ENSETUP.EXE is the current subdirectory when running either ELNEC or
ENSETUP, by typing 'CD \ELNEC' at the DOS prompt before running the
program.
Not all the frequency sweep steps show up in MicroSmith when I
import the .DAT file
ELNEC limits the number of frequency steps written in the .DAT file
because some versions of MicroSmith can handle only a limited number.
MicroSmith version 2.000B can handle only eight steps in imported .DAT
files, while later versions can handle many more. The maximum number
of steps written into the .DAT file can be set with ENSETUP (see p.
13). If you have MicroSmith version 2.000C or later, you should set
the limit to 100 or other value specified in your MicroSmith
documentation.
The screen is blank or the plot or grid is invisible:
A bad choice of colors has been made. You can change colors by running
ENSETUP or you can erase the file ELNEC.CFG which will force use of
the default colors.
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The program crashes when it's started or when a file is recalled:
ELNEC won't permit you to save a defective file. When a file is
written, a code number is included and this number is checked whenever
the file is read. If it's incorrect the file won't be accepted and the
"Default" antenna is shown instead. It's highly unlikely, but
possible, that a file could be corrupted without changing the code
number. If this were to happen to the LAST.EN file, which is read and
processed each time the program starts, a crash could happen. The cure
for this would be to erase the LAST.EN file and any accompanying
calculated array files going to the .EN subdirectory and typing 'del
last.*'. Likewise, a file which causes crashing when read has been
corrupted and should be erased. Again, calculated array files also
should be erased by typing 'del filename.*' where filename is the name
of the file without the extension. This is an unusual circumstance but
has happened.
The program crashes under any other circumstances:
A large amount of effort has gone into making ELNEC "crash-proof."
There should be no condition or action on the user's part which causes
a program crash. (Exceptions: Turning off the printer during printing
will cause a crash. It wasn't felt that prevention of this occurrence
was worth the reduction in plot printing speed and increase in code
size. Also, entry of values outside the range of +/- 1E-38 to 1E+38,
except zero, can cause a crash. This never should be necessary.)
Unfortunately, one source of program crashing hasn't been preventable.
IIT (Integrated Information Technologies) coprocessors sold for a
period of time contain a "bug" which will cause ELNEC to crash. Newer
chips have the bug fixed. If you have this brand coprocessor and
encounter a crash, please contact me for information about obtaining a
replacement. If you encounter a crash for any other reason, please
record the error message. If it's possible to duplicate the crash,
record the sequence of events leading up to it. If a particular
description file is involved, print the description using 'PD' in the
Main Menu. Send or fax the information to me and I will find and
correct the problem as quickly as possible and send you a corrected
copy without charge.
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ERROR MESSAGES
ELNEC error messages are intended to be as self-explanatory as
possible. However, more information sometimes is useful, so some
messages include an "ELNEC error" number. This section gives more
information about what causes the error and how to avoid or correct
it. Following the numbered errors is additional explanation of several
others.
ELNEC error 1
ELNEC is unable to start in the TraceView mode because it can't recall
a primary trace file. ELNEC is looking for a file with extension .ENT
in the .EN files directory, and is unable to locate one, either
because of difficulty accessing the .EN files directory, or because no
.ENT files are present in the directory. If you haven't saved any .ENT
(trace) files when running ELNEC, you will get this result;
TraceView's purpose is to view these traces. If the problem is caused
by inability to access the directory, correct the problem described in
the message. The .EN files directory can be changed with ENSETUP or
from the Options Menu in ELNEC, but at least one trace file must be in
the directory for TraceView to run.
ELNEC error 2
When calculated array files are recalled, they are put into arrays for
ELNEC to use. These arrays reside in RAM. If insufficient RAM is
available to load them, it means that more RAM was available when the
calculations were originally done than is at present. When this
happens, ELNEC will load the antenna description, but not the
calculated arrays. However, you'll probably find that ELNEC won't
perform calculations on the antenna because it will detect that not
enough RAM is available. For more information on how to make more RAM
available, see MEMORY CONSIDERATIONS, p. 10.
ELNEC error 3
The antenna contains too many "pulses" for ELNEC to analyze. The
number of pulses approximately equals the total number of segments.
ELNEC is limited to 127 total unless the Maximum Pulse Option is
present. The only way to make a significant reduction in the number of
pulses is to reduce the number of wire segments. For more information
on pulses, and a technique for doubling the number of available
pulses, see pages 100 and 32.
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ELNEC error 4
Insufficient free RAM is available to run ELNEC. You will have to make
more RAM available or reduce the antenna complexity. Reducing the
total number of segments will have the greatest effect. For more
information on RAM and how to make more available, see MEMORY
CONSIDERATIONS, p. 10. If you exit ELNEC by typing 'QU' from the Main
Menu in order to free more RAM, the antenna description will be saved
and reloaded when you restart ELNEC.
ELNEC error 5
ELNEC was unable to access the default .EN directory. This directory
is specified by running ENSETUP or by choosing it in the Options Menu.
If this error occurs, you must either correct the problem shown in the
error message or change the .EN directory.
ELNEC error 6
When ELNEC ends, it saves the current antenna description in file
LAST.EN in the .EN file directory. This error occurs when it is unable
to do so. If you can't correct the problem shown in the error message,
you must either change the .EN file directory (selection "EN" in the
Options Menu) or exit the program by typing 'EX'. If you do the
latter, the antenna description will not be saved.
ELNEC error 7
This message will occur if you have selected "Save all calculated
arrays" for selection "LF" in the Options Menu and insufficient disk
space is available to save them. When this option is chosen, ELNEC
saves calculated arrays with the LAST file in the .EN directory when
the program ends. You must either change the .EN path to a drive with
enough space (Options Menu selection "EN") or change Options Menu
selection "LF" to "Save description only". If you do the latter, the
calculated arrays won't be saved, and calculations will have to be
redone when ELNEC is restarted.
ELNEC error 8
An error was encountered while writing ELNEC.CFG. This file contains
the information specified by the Options Menu and the ENSETUP program.
ELNEC.CFG is always written in the current directory (the directory
you were in when you started ELNEC). All that can be done is to
correct the error reported by ELNEC. Until the problem is corrected,
no changes can be made to ELNEC.CFG.
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ELNEC error 9
ELNEC had trouble reading the file LAST.EN. This file always is
written when ending ELNEC with 'QU'. It contains the antenna
description present when ELNEC ended, and is automatically read when
ELNEC starts. LAST.EN resides in the directory specified by ENSETUP or
by Options Menu selection "EN". If you see this error, ELNEC will be
unable to save or recall antenna descriptions until the .EN file
directory is changed to one which can be accessed or the problem is
corrected.
ELNEC error 10
An illegal extension was specified for an antenna description file or
a trace file. Extensions .V, .I, .DB, and .Z*, where "*" is any
combination of characters, are reserved for calculated array files.
You won't be permitted to save, recall, or delete files with these
extensions. Files with other extensions can be recalled or deleted,
except that files with the extension .EN can't be recalled as a trace
file, and files with extension .ENT can't be recalled as an antenna
description file. Antenna description files must have the extension
.EN, furnished either by ELNEC or the user, to be saved. Trace files
must have the extension .ENT to be saved.
The following errors occur only when ELNEC is operating in conjunction
with the Maximum Pulse Option, MaxP. They are included here because
they are generated by ELNEC.
ELNEC error 11
Sufficient disk space isn't available to write one or more of the
Frequency Sweep output files. The message will tell you which file
there was insufficient space for. Go to the Options Menu to see what
path was chosen for the file in question. You can either change the
path to a different disk drive or make room on the selected disk by
erasing some files.
ELNEC error 12
Too many frequency steps were specified. ELNEC is able to plot only a
limited number of points on the screen due to array size limitations.
The total number of points is determined by the number of frequency
steps (in general, equal to ((start freq - stop freq)/freq step) + 1)
and the number of points per plot (((end angle - start angle)/step
size) + 1). Either a smaller number of frequency steps must be
specified (by reducing the frequency range or increasing the step
96
size) or the number of points per plot must be reduced (by reducing
the plot range or increasing the plot step size). Or, you may choose
to not save the plots from the frequency sweep (Frequency Sweep Menu
selection "PN").
ELNEC error 13
This error is caused by specifying too many total points for ELNEC to
plot (see error 12, above). If frequency sweep is off, you must reduce
the number of plot points by reducing the plot range or increasing the
plot step size. If frequency sweep is on, you can also reduce the
number of frequency steps by specifying a smaller frequency range or
increasing the frequency step size, or by choosing not to save
frequency sweep plots.
ELNEC error 14
ELNEC is able to plot only a limited number of points on the screen
due to array size limitations. The number of recalled traces which can
be viewed simultaneously depends on the number of plot points per
trace.
ELNEC error 15
ELNEC can't accommodate more than 1500 plot steps in a single plot. If
you see this error, you must either reduce the plot range or increase
the plot step size.
ELNEC error MP1
ELNEC was unable to find one of the temporary files recorded by MaxP,
so is unable to make use of the data it has calculated. This file is
recorded in the directory specified by selection "MA" in the Options
Menu. The only cause for this error I can foresee is if the MaxP
directory is on a floppy disk and the disk is removed during program
execution. Please notify me if you see this error.
ELNEC error MP2
When you change the directory for the temporary MaxP files, ELNEC
attempts to copy them from the old directory to the new one. (If
successful, it then erases the files in the old directory.) This
error occurs if ELNEC was unable to copy the files. When this happens,
it leaves the MaxP temporary file directory unchanged.
97
ELNEC error MP3
When MaxP has run and you choose to save the calculated arrays, ELNEC
copies the temporary files containing the impedance data from the MaxP
temporary directory to the .EN file directory. This error occurs if
ELNEC is unable to find the temporary files in the MaxP directory or
if it is unable to access the MaxP directory. There is no obvious
fault which would cause this error; please notify me if you see it.
ELNEC error MP4
ELNEC is unable to write the temporary MaxP files to the MaxP
temporary file directory for the reason shown in the error message.
The MaxP temporary file directory can be changed with selection "MA"
in the Options Menu. The temporary files which ELNEC writes are small
-- two are 512 bytes and the third seldom exceeds 2k or so. However,
before running MaxP, ELNEC makes sure there's enough disk space to
hold the large temporary arrays that MaxP will generate. The required
space may exceed 500k bytes. The only solution is to specify a drive
for the MaxP temporary file path which contains adequate space.
ELNEC error MP5
When calculated array files are recalled from antennas containing more
than 127 pulses (arrays calculated by MaxP), they aren't loaded into
ELNEC but are copied into the MaxP temporary files directory as
temporary files. This error occurs when ELNEC is unable to copy them
into the MaxP temporary file directory. You must correct the problem
shown in the error message or change the MaxP temporary file path with
selection "MA" in the Options Menu to a drive/directory which can be
accessed and which has adequate room.
Zero-length wire(s)
If zero-length wires are present, ELNEC can't place sources or loads
properly or do other essential calculations. Therefore you aren't
permitted to leave the Wires Menu while this problem exists. When you
attempt to leave, however, you're given the option of deleting all
zero-length wires. Agreeing to the deletion will clear the error and
permit you to return to the Main Menu.
98
Other errors:
Wire(s) in or on the ground plane
If a real or perfect ground has been specified, wires aren't permitted
to extend into the ground plane (negative z-coordinate) or lie on the
ground plane (both z-coordinates zero). If this condition exists,
ELNEC can't perform calculations and you're prevented from running the
program or saving the antenna description. You also can't exit ELNEC
using (QU)it from the Main Menu because this would save the defective
description in the LAST file. If you don't want to correct the problem
by changing the ground type or wire coordinates, you can exit the
program by typing 'EX' at the Main Menu.
Source(s) or load(s) on a nonexistent wire or open wire end
This condition prevents ELNEC from correctly performing calculations.
One circumstance which can cause this error is to delete all wires
which have sources placed on them. ELNEC will leave one source (since
one source is required) but place it on a nonexistent pulse. Like the
above error, it will prevent you from running ELNEC, saving the
antenna description, or exiting using (QU)it. If you want to exit the
program without fixing the problem, use (EX)it in the Main Menu.
"Internal error"
This usually appears as "Internal errorInternal error" and the user is
returned to DOS. It is caused when the coprocessor type of ELNEC is
run on a machine which has no coprocessor or a non-functioning
coprocessor. Not many programs make use of a coprocessor, and few
require one, so it's very possible to not realize that a coprocessor
is non-functional. Most 80386 and earlier computers require that a DIP
switch be changed when a coprocessor is installed. If you encounter
this error, it's possible this wasn't done. The BIOS in some 80486
machines has the provision for enabling and disabling the coprocessor.
If you see this error on a 486DX machine, run the setup program
provided with your machine and see if the coprocessor is disabled.
Note that 80486SX processors don't have a functional built-in
coprocessor, but 80486DX processors do.
"Error xx occurred in module XXXXXXXX at address xxxx:xxxx"
This is a "crash". It's accompanied by program termination and return
to DOS. Please see the section above on crashes. Be sure to read it
carefully if you have an IIT brand coprocessor.
99
PULSES
Perhaps the nicest thing about ELNEC is that you don't have to
understand "pulses", and how MININEC numbers them, to use it. However,
pulses are fundamental to the computation method so the term appears
here and there in ELNEC. Their significance in source/load placement
is explained in "The Sources Menu" above. The other place where they
have particular significance is in determining the size of an
important internal array, the impedance array. The size of this array
can't exceed 127 pulses unless the Maximum Pulse Option (MaxP) is
used. If your antenna description includes more than 127, ELNEC will
tell you so and refuse to perform the calculations. The number of
pulses is closely related to the total number of wire segments, so if
the number of pulses exceeds 127, fewer wires, or wires having fewer
segments, must be specified. More information on pulses can be found
in "MININEC: The Other Edge of the Sword", in February, 1991 QST, and
in the MININEC manual referenced at the end of this chapter.
NOTES FOR EXPERIENCED MININEC USERS
ELNEC describes antenna and ground radial wires by diameter instead of
radius. This was done because wire tables generally give diameter, and
tubing is usually measured by diameter. ELNEC uses elevation angle
(measured upward from horizontal) rather than zenith angle (downward
from vertical). Although zenith angle is mathematically cleaner, I
found myself having difficulty thinking in terms of zenith angle so
changed to elevation instead. Media boundaries are entered
differently; you enter the beginning boundary of the medium being
described rather then the boundary of the next medium. MININEC doesn't
permit radials if only one medium is specified; ELNEC does, and
assumes infinite radial length in that case. And as explained
elsewhere, if source/load positions are defined by wire number and
position in wire (as recommended), the source and load positions will
behave differently than in MININEC as geometry is changed.
When you select source or load data, powers are shown. The powers
shown by ELNEC are exactly twice those shown by MININEC. MININEC
apparently interprets source voltages as peak values, while ELNEC
interprets source voltages and currents as rms.
If you compare MININEC results to those of ELNEC with the Parallel
Wire Correction off, you'll find small differences (typically 0.01 dB
or so). This is because ELNEC uses precise values for the speed of
light and the permittivity of free space to calculate derivative
100
units, while MININEC uses several constants of various precision to
define derivative units. Also, certain calculations are done in a
different order, changing cumulative errors. Differences with the
Parallel Wire Correction on can be slightly greater, but not
significant except where MININEC is having difficulty doing the
calculation correctly.
You may find substantial differences in ELNEC and MININEC far-field
results if you have described a multi-media ground with the media at
different heights. ELNEC contains a correction for the simplified way
MININEC uses to determine reflection point. This is briefly described
in "MININEC: The Other Edge of the Sword", in February, 1991 QST.
No more fussing with pulses! You'll love ELNEC's source/load entry
system and smooth handling of wire/source/load changes.
MORE MININEC INFORMATION
If you would like to learn more about the mathematics, basic
functioning, and limitations of MININEC, obtain a copy of
The New MININEC (Version 3): A Mini-Numerical Electromagnetic Code,
by J.C. Logan and J.W. Rockway, Naval Ocean Systems Center, San
Diego, CA (NOSC Technical Document TD 938)
It can be ordered as NTIS document number ADA181682 from
National Technical Information Service
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650
This is a highly technical manual.
A comprehensive article on the limitations of MININEC and its
derivatives such as ELNEC is "MININEC: The Other Edge of the Sword",
in February, 1991 QST. Although much of its content is included in
this manual, I recommend reading it. (For one thing, it has the major
advantage of containing pictures!)
101
HELP!
As a customer, you have the right to expect a program you can use. If
you encounter a problem with ELNEC, I'll do everything I can to
resolve it. Before contacting me, however, please consider that I'm
employed outside the pursuit of writing and supporting ELNEC which
limits the total time I have available. I've tried to anticipate as
many questions as possible in the manual; please first try to find the
answer to your question here. If you can't find the answer in the
manual, write to me at the address below, call (503)646-2885 (I'm on
Pacific time), fax (503)671-9046, or email w7el@teleport.com and I'll
be glad to help you -- but only if you've consulted the manual first!
It's my sincere intent to make ELNEC as intuitive and easy to use as
possible while retaining the impressive power of MININEC's method-of-
moments analysis. If you have any suggestions for improvements or
would care to comment on anything you like or don't like about the
program, I would very much appreciate hearing from you. I would
especially like to know if you've observed any malfunctioning,
unpredictability, or program "crashing". These are not acceptable and
will be corrected as soon as the cause is discovered. Later versions
will be offered to current users at a substantial discount.
Thanks for choosing ELNEC. Good luck with your antenna projects!
73,
Roy Lewallen, W7EL
P.O. Box 6658
Beaverton, OR 97007 U.S.A.
102
I N D E X
.DAT files 79, 88
maximum number of frequency steps 14, 16, 79, 92
.DB files 89
.EN (antenna description) files 13, 71, 86, 88
extension 85
path 14, 15, 91
path, default 14, 56
.ENT (trace) files 13, 71, 88
extension 71, 85
path 14
path, default 14, 56
.F(#) (frequency sweep trace) files 13, 89
.GAM files 79, 88
contents 79
.I files 89
.V files 89
.ZI files 89
.ZR files 89
386MAX 31
Adding wires, sources, loads, media 83
Aluminum
alloy, resistivity 50
ANALYZE 53, 70
and TraceView 86
resolution 51
Antenna
Crossed dipoles 25
ground plane 30, 33
viewing 55, 61, 71
Antenna description
abbreviated, printing below plot 55
deleting 85
recalling 85
saving 85
ANTNOTES.DOC 13, 88
AUTOEXEC.BAT 31
Axis lines
in View Antenna display 72
Azimuth angle 29, 48, 50
Azimuth plot
description 28
Beamwidth 53, 70
Browse 52
103
Calculated arrays
saving 52, 85, 89
saving with LAST 57, 89
Color
background 14, 15
plot 14, 16
recalled trace 14
Colors
view antenna display 76
Computation, speeding up 31
Conductivity
scaling 33
CONFIG.SYS 31
Coordinate system 48
origin 73
Coprocessor
Absent or non-functioning 99
IIT brand 99
IIT brand and crashes 93
Copy protection 5, 9
Copying wires, sources, loads, media 83
Copyright 6
Crash, program 93, 99, 102
Crossed dipoles 25
Current
abrupt changes 22, 30
and segments 22
importance of 30
interpreting 30
phase of 26
polarity 30
symmetry 30
Current directory
defined 37
Current phase indicators 76
Currents
viewing 75
Data files
path, default 56
Date format 14
dBd 34
dBi 34
Default antenna 91
Deleting
antenna descriptions 52, 85
traces 71
104
Deleting wires, sources, loads, media 83
Directories 87
Directory
current, defined 37
starting ELNEC from a different 37
Disk drive requirements 13
Elevation angle 28, 48, 50, 100
Elevation plot
description 29
ELNEC
ending with QUit 55
exiting without saving in LAST 55
files 87
limitations of 101
starting 37
ELNEC.CFG 13, 16, 55, 76, 88, 92
default values 14
ELNEC.DOC 13, 88
ELNEC.EXE 13, 19, 88, 91, 92
EMM386 31
ENSETUP 86, 92
running 13
ENSETUP.EXE 19, 88, 92
Error messages 94
"Internal error" 99
maximum pulse option 96
Errors
sources/loads on nonexistent wire 99
sources/loads on open wire end 99
wire coordinate 64
wires in or on ground plane 99
zero-length wires 98
EXit 55, 99
Extended/expanded memory manager 31
Field strength
units 57
Field(s) to plot 51
Files
ELNEC 87
MicroSmith 79
saving, recalling, deleting 84
Filling cells 83
Frequency 49
Frequency sweep 53, 78
data output file 80, 81
data output file, contents 81
105
menu 78, 80
MicroSmith files 81
pattern plots (traces) 80
Front/back ratio 53, 70
quad antenna 24
Front/side ratio 53, 70
Front/sidelobe ratio 53
Gain 70
-99.99 dB 90
antenna over ground 32, 35
ELNEC vs MININEC 100
forward 53
reference 35, 52
Graphics adapter 9, 91
Ground 70
conductivity 68
conductivity and dielectric constant, table 68
conductivity, default 56, 68
connecting loads to 66
connecting sources to 66
connecting wires to 28, 60
dielectric constant 68
dielectric constant, default 56, 68
height 69
modeling 27
perfect 27
radials 28, 68
radials, adding or changing 70
real 27
real, limitations of model 27, 67
shielding effects 28
specifying 67
Ground description, real 50
Ground plane antenna 30, 33
Ground system
efficiency 27, 70
Ground type 49
Ground wave 18, 29
Grounded segment correction 8, 18
Group dia. 60
Group edit 61, 82
Group fill 83
Guarantee 6
Hardware requirements 9
Height, antenna
changing 61
106
Help
how to get 102
Highlight wire 75
Horizontal antennas, low 27
HPIB 10, 90
IIT brand coprocessor 99
cause of crash 93
Impedance
feedpoint 29, 54
source 29, 54
user-defined, for SWR 52
Installation 13
Inverted vee antenna 41, 59
Isotropic radiator 34
Laplace transform
automatic RLC entry 67
using 66
LAST.EN 55, 88
and TraceView 87
defective 93
not found 91
saving calculated arrays with 57, 89
Letters, lowercase and uppercase 47
License agreement 6
Load data 31, 54
Loading coils 26, 27, 31
Loads 49
adding 66
at junctions of more than two wires 33
connecting to ground 66
deleting 66
impedance, specifying or changing 66
Laplace transform 66
loss 31
on nonexistent wire 99
on open wire end 99
position of, specifying 66
position of, specifying pulse number 66
using 26
Loads Menu 66
Log periodic antenna 24
Loop
quad 23, 25
Loss
load 31
LPT1: 13
107
Main Menu 48
Maximum Pulse Option (MaxP) 8, 9, 25, 56, 86, 89, 94, 100
description 10
error messages 96
MaxP files
path, default 56
MAXP.EXE 37
Media 28
adding 69
boundary 68
boundary, changing type 69
deleting 69
height 69
multiple, at different heights 101
multiple, example 68
Memory
expanded and extended 10
Memory requirements 9, 10
Menus 48
Loads Menu 66
Main Menu 48
Media Menu 67
Options Menu 55
Plot Menu 70
Sources Menu 64
View Antenna Menu 71
Wires Menu 58
MicroSmith 79, 89
maximum number of frequency steps 14, 16, 79, 92
ordering information 89
MicroSmith files 14, 16, 79, 81, 88
path, default 56
MININEC 5, 8, 9, 18, 22, 24, 27, 33, 57, 67, 70, 100
limitations of 8, 18, 21, 24, 27, 57, 67, 101
manual 101
notes for experienced users of 100
MININEC: The Other Edge of the Sword 21, 100, 101
Modeling 20
antenna structure 21
complex structures 34
Monitor
color 16
LCD 14, 16
monochrome 14, 16
Moving wires, sources, loads, media 83
MSHERC.COM 13, 88
108
Multiband antennas 25
NoFlash 78
Notebook computers 74
Options Menu 55
Origin
coordinate system 73
Output files
path, default 56
Parallel wire correction 57
Pattern plots
viewing with antenna 77
Patterns 28
frequency sweep 79
Permeability
wire, specifying 50
Phase indicators 76
Phase, current 75
Phased array antenna
feed systems 26
Phased array antennas 26
Plot
distorted 91
distorted, printed plot 91
garbled, printed plot 91
generating 53
grid style 57
outer ring value 51, 57
printing 71
style 57
Plot Menu 70
Plot type 50
Plot/table range 51
Plotters 9, 90
Polarization 51
Power
ELNEC vs MININEC 100
loss in loads 31
Preserve connections 62
Primary trace 86
Printer port 9, 13, 15, 90
Printers 13, 89
dot matrix 14
Epson FX 14, 89
Epson LQ 14, 89
Epson MX 15, 89
HP DeskJet 15, 89
109
HP LaserJet 14, 15, 89
HPIB 90
IBM 14, 89, 91
laser 15, 89
serial bus 90
types 14
Problems 90
-99.99 dB gain 90
% sign in menu entry 91
blank screen 92
default antenna 91
distorted plot 91
distorted printed plot 91
ENSETUP has no effect 92
frequency sweep traces all white 90
garbled printed plot 91
graphics adapter not detected 90
grid but no plot 90
MicroSmith .DAT file frequency steps 92
negative printed plot 91
program crashes 93
Pulses 9, 100
doubling the number of 32
maximum number of 25, 32, 100
viewing 77
QEMM386 31
Quad antenna 24
front/back ratio 24
Quad loop 23, 25
QUit 55, 99
Radials
ground 28, 67, 68, 100
ground, length and diameter 33, 49, 50, 100
ground, program limitations 27, 70
ground, specifying 67, 70
ground-plane antenna 30, 33, 59
RAM 9, 10
READ.ME 13, 88
Real ground description 50
Recall Trace 87
Recalling
antenna descriptions 52, 85
traces 71
Resistance
low 29
negative 29, 54
110
Resistivity
wire, scaling 33
wire, specifying 50
RLC, series or parallel, entering 67
Saving
antenna descriptions 52, 85
traces 71
Scaling 33, 49
Scientific notation 47
Segment
length of 75
Segments 22, 72
and accuracy 22
and computation time 22
length limits 22, 25
number of, choosing 22, 23, 25, 30, 32
number of, entering 60
number of, total 60
tapering 32, 62
Sidelobe 53, 70
Significant digits, number of 47
Skin effect 50
Source data 54
Sources 49
adding 65
amplitude and phase 65
at junction of two wires 26
at junctions of more than two wires 33
connecting to ground 66
current 26, 65
deleting 65
multiple 26
on nonexistent wire 99
on open wire end 99
polarity 26
position of, specifying 64
position of, specifying pulse number 65
using 25
voltage 26, 65
Sources Menu 64
Step size 51
SWR 29, 52, 54
Templates 34
Test drive 37
Time remaining display 47
Tips 31
111
Title 49
Top view 55
Trace
clearing 71
deleting 71
recalling 71
saving 71
viewing with antenna 72, 76, 77
Traces
frequency sweep 79
TraceView mode 86
ending 87
starting 37, 86
Traps 26, 27, 31
TSR programs 10
Units 50
changing 62
changing without changing numbers 62
Upgrading from earlier versions 17
V/m 57
View Antenna 9, 18, 29, 48, 55, 61, 71
highlight wire feature 75
operation 72
viewing current phase 30
viewing currents 30
View Antenna Display and Menu 71
Wild card 71, 85
Wire Coordinate Errors 64
Wire gauge 49
radials 70
wire diameter, specifying as 60
wire diameter, specifying as, example 39
Wire grid 23
Wire loss 29, 50
Wires 21, 49
adding 60
closely spaced 22, 24
connected 72
connecting 60
connecting to ground 28, 60
connecting to other wires 22, 58, 59
coordinates, changing 84
deleting 61
diameter, changing group 60
diameter, entering or changing 60
diameter, limits 21
112
diameter, specifying as wire gauge 60
diameter, specifying as wire gauge, example 39
direction 26
end coordinate, errors 64
end coordinates 21
end coordinates, entering 58
end coordinates, specifying 26
highlighting in View Antenna display 75
in or on ground plane 99
joining at an angle 22, 23, 32
length, changing 59
permeability 50
preserving connections 62
renumbering 61
resistivity 50
rotating 59
rotating, example 43
unconnected 72
zero-length 98
Wires Menu 58
Zenith angle 100
Zero-length wires 98
Zoom
view antenna 74
113