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RFC15.TXT
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1994-04-06
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RFC rel. 1.5 USER MANUAL
written by Giorgio FONTANA
Topics : 1) How to use RFC.
2) Examples.
1) HOW TO USE RFC.
AGREEMENT:
Create a file named agreemen. with 2 carriage return typed into it.
Eventually delete the string stored in this file.
CONFIGURATION:
RFC can be configured by editing the file RFC.CFG.
RFC.CFG is an ASCII file which contains 10 lines, extra lines are not
considered by the program. RFC.CFG must be in the directory of
RFCxx.EXE and RFC.PIC.
RFC.CFG contains the following information:
The speed of light in Km/ms 299.792
The number of points per arc 20 (1 to 100 allowed)
The data drive and directory (space or string like c: c:\rfc\ ...)
The language switch E (E=english,I=italian,N=on line select)
The keyboard autorepeat rate 0 (0 to 31, 32 disables, 0=fastest)
The logout autorepeat rate 0 (0 to 31, 32 disables, 0=fastest)
The palette color for Z map 1 (0 to 63)
The palette color for Y map 2
The palette color for R map 4
The palette color for Q map 56
Comments
RFC.CFG could be omitted obtaining:
The speed of light in Km/ms 299.792
The number of points per arc 20
The data drive and directory same as RFC.EXE
The language switch N
The keyboard autorepeat rate 32
The logout autorepeat rate 32
The palette color for Z map 1
The palette color for Y map 2
The palette color for R map 4
The palette color for Q map 56
DEFAULT UNITS: ohm, mho, pF, uH, meters, dB/m, MHz, degrees.
STARTING RFC:
Once configured the program can be started typing RFC14.
Now the summary of the commands is presented to you. The summary can be
recalled later by the command <?>.
Please choose the characteristic impedance of the chart, which is the
impedance that corresponds to the center of the chart, where the reflection
coefficient is zero.
Then choose the frequency.
On the left side of the screen there is the complex plane of the
reflection coefficient. A graphic cursor can be moved in the plane using the
arrow keys. The impedance, admittance, reflection coefficient, and Q charts
can be displayed using <F1>, <F2>, <F3>, <F4>.
On the right side of the screen an info display shows the coordinates of
the cursor in many equivalent forms. Press <O> and <P> to get other
equivalent quantities.
The info display is linked to the cursor when the cursor is moved. The
info display shows the start impedance when the start impedance is defined
with <I> or when a network is loaded from the disk. The info display shows
the impedance at the end of the arc associated to the element selected by
<F6> if <F6> is used. The info display shows the impedance at the end of the
network if the element selected by <F6> is the last element of the network.
HOW TO DEFINE THE START IMPEDANCE:
The start impedance can be defined by moving the cursor to the start
impedance and typing <F9> to set the impedance. A red square is placed
around the cursor.
The start impedance can be defined numerically with the key <I>.
You can choose among impedance, admittance and reflection coefficient. If
you choose impedance or admittance, you are allowed to select an equivalent
circuit RL or RC. If you do so, the start impedance is frequency dependent.
Using <I> the impedance selected can be outside the plane.
HOW TO ADD ELEMENTS TO THE START IMPEDANCE:
Elements can be added using <F8>. Elements L, C and Z can be added
in series or in parallel to the preceding element. Element T (transmission line)
can be connected as transmission line or stub. Element M (ideal transformer)
can be connected as transformer with common grounds. Key <=> shows the
schematic of the network.
You can redefine an element by selecting it with <F6> then press
<F8>.
HOW TO TUNE AN ELEMENT:
A couple of keys is associated to each element, see the Key field of the
info display. Using the Keys (upper and lower case) you can trim the values
of up to 2 parameters of the element:
Element Upper case Lower case
first parameter second parameter
C capacitance
L inductance
Z resistance reactance
T lenght characteristic impedance
M turn ratio
The info display shows the value of the last parameter that has been trimmed.
All the parameters of an element can be displayed selecting the element with
<F6> then press <U>.
HARDCOPY:
<W> prints the listing of the network and the hardcopy of the graphic
display (big) or the hardcopy of the screeen (small). HP Laserjet and Epson
formats are supported.
AUTOTUNING:
To reach a given impedance with your network, first choose the
impedance with the cursor, then press <#>.
Autotuning tunes the first parameter of each class of elements.
An element can be locked using <F6> to select it and </> to lock and unlock.
If the number of unlocked elements is >2 then the Q of the network is
minimized too, but the procedure may not converge exactly to the desired
impedance, to correct lock one or more elements.
Autotuning works with a fixed number of iterations, sometimes it is
necessary to call it more than once.
MONTECARLO SIMULATION:
<F10> starts a Montecarlo simulation for tolerance evaluation.
Type the tolerance in +- xx% for the parameters required by the program and
choose the number of simulations. The program shows the end impedances
marked with green points. The numer of different points is shown in the info
display. The area plot can be erased and recalled using <^>.
FREQUENCY SWEEP:
<!> starts the frequency sweep. The plot can be erased and recalled
using <^>.
<^> : the buffer is preserved to compare the behaviour of different
networks.
CIRCLE DRAWING:
To draw a circle move the cursor to the center of the circle and press
<T>, a green point shows the center of the circle. Then move the cursor to a
point on the circumference of the circle and press <T> again, a circle is
drawn. Now the key <t> erases and recalls the last circle drawn.
HOW TO MARK A POINT:
Move the corsor to the point and press <Y>. The same Key deletes the
point.
CALCULATOR FOR COMPLEX NUMBERS:
The key <$> recalls a calculator for complex numbers. The buffer of
the calculator is ratained and saved with the network data file.
Select the operation with <+>, <->, <*>, </>, <L>, <E>, select the
field with <space>, <\>, <tab>, enter a number with <enter>, NUMBER,
<enter>, select the mode with <>> and <<> (modulus and phase (degrees) or
real and imaginary parts).
HOW TO SAVE A NETWORK ON DISK:
Type <ctrl-S> and choose a six (maximum) digit code for the network.
HOW TO RECALL A NETWORK FROM DISK:
Type <ctrl-R> and type the code of the network.
ONLINE SELECTION OF THE NUMBER OF POINTS PER ARC.
Arcs are constructions that give a better feeling of the behaviour of
an element of the network. Type <ctrl-P> to select a number of points between 1
and 100. The program is faster with few points per arc.
HOW TO SELECT A NEW FREQUENCY:
<F5> allows to select a new frequency. <-> and <+> can be used to
step the frequency by 1, .1 or 10 MHz, the step depends on <F7>.
HOW TO CHANGE THE STEP:
<F7> changes the step for the tuning of the elements and frequency.
At the beginning the step is 1 % and 1 MHz. The values are circled through
.1%, .1MHz and 10% , 10 MHz.
HOW TO RESET THE PROGRAM:
<r> resets the program. Confirmation required
HOW TO QUIT THE PROGRAM:
<q> quits the program. Confirmation required
2) EXAMPLES
1) FIND THE COEFFICIENT OF REFLECTION OF A RC SERIES
CIRCUIT. f=100 MHz, Zo=50 ohm, R=10 ohm, C=50 pF.
SOLUTION:
Start the program.
Zo=50
Fo=100
<I>
<I>
10
<C>
50
Read the info. display and press <O> and/or <P> to read different quantities.
2) MATCH A LOAD WITH REFLECTION COEFFICIENT .1905 ANGLE
324.55 TO 50 OHM RESISTIVE. Fo=188 MHz, USING A 50 OHM
TRANSMISSION LINE AND A 50 OHM OPEN SERIES STUB.
Zo=50
F0=188
<I>
<C>
.1905
324.55
<F8>
<T>
.59
50
1
0
<0>
<F8>
<T>
.47
50
1
0
<1>
<#>
Press <F6> twice to read the end impedance.
Find a better solution (using shorter lines).
3) FIND THE FREQUENCY PLOT OF A SERIES RLC CIRCUIT.
Zo=50 Ohm, R=5 Ohm, C=10 pF, L= 1uH, F= 30 TO 60 MHz, step .1
MHz.
Zo=50
Fo=50
<I>
<I>
5
<C>
10
<F8>
<L>
1
<S>
!
30
60
.1
Try <^> when finished.
Find the resonant frequency of the circuit using <+> and <-> , type <F7> to
reduce the frequency step to .1 MHz. (50.3 Mhz).
4) FIND THE FREQUENCY PLOT OF A TRANSFORMER WITH L1=1uH,
L2=4uH, k (coupling factor)=.6 CONNECTED TO 50 Ohm RESISTIVE.
f=1 TO 20 MHz.
Using a simplified equivalent schema:
k=M/SQR(L1*L2)
M= K*SQR(L1*L2)=2*.6=1.2uH
Ls=L1(1-k^2)=1*.64=.64uH
Lp=k^2*L1=.36uH
N=L2/M=4/1.2=3.33
Zo=50
Fo=10
<ctrl-P>
80
<F9>
<F8>
<L>
.64
<S>
<F8>
<L>
.36
<P>
<F8>
<M>
3.33
<=>
<space>
!
1
20
.1
RFC is a CALCULATOR.
The PHYSICS and ELECTRONICS of electromagnetic fields, waves and
devices must be the background of RFC users.
See for example:
'Foundation for microwave engineering' R.E. Collin - McGRAW-HILL.
and
'ELECTRONIC APPLICATIONS OF THE SMITH CHART' P.H. Smith, copyright
by Analog Instruments Co., New Providence, N.J.