QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940089.txt

Internet Message Format | 1994-11-13 | 19KB

Date: Sun,  3 Apr 94 04:30:13 PDT
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #89
To: Ham-Ant


Ham-Ant Digest              Sun,  3 Apr 94       Volume 94 : Issue   89

Today's Topics:
                       AEA Hot Rot whip for HT
                      Antenna stacking problems
                             Attic Dipole
                         CQ Article on HS-100
                         CQ Article on TH11DX
                  Discone vs 5/8 wave for 2m packet?
                 How to base-feed half-wave vertical?
               Super-conducting antenna (LONG) (2 msgs)

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Archives of past issues of the Ham-Ant Digest are available
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We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
----------------------------------------------------------------------

Date: 3 Apr 94 02:33:08 GMT
From: dog.ee.lbl.gov!agate!usenet.ins.cwru.edu!odin![e-mail]
Subject: AEA Hot Rot whip for HT
To: [e-mail]

In article <ah301-290394073455@sy_j.pgh.wec.com>,
Jerry Sy <[e-mail]> wrote:
>I tested it on an swr meter and its swr is > 3, my rubber duck is < 1.5 !

You can tune it by adjusting the length, checking it on the meter until
you find something < 1.5.  Scribe that length into the side of the antenna
so you can find it again without the meter.

BTW, there is usually no need to cross-post so widely.  I've set followups
to just rec.radio.amateur.antenna.

       Stephen

--
Stephen Trier  KB8PWA       "It don't mean a thing if it ain't got that
Other: [e-mail]     certain je ne sais quois."
Home: [e-mail]                         - Peter Schickele

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Date: 2 Apr 1994 23:51:02 -0500
From: agate!howland.reston.ans.net!news.ans.net!hp81.prod.aol.net!search01.news.aol.com![e-mail]
Subject: Antenna stacking problems
To: [e-mail]

In article <[e-mail]>, [e-mail] (James N. Price)
writes:

HI I HAD A TH3 AND KLM ROTATABLE 40 M DIPOLE AND 15 METER DID NOT WORK VERY
WELL ON THE TH3 UNTILL I MOVED THE 40 ANT 90 DEGREES AND IT WORKED GREAT AFTER
THAT... I THINK THAT THE ANTS WERE ABOUT 4 FEET APART ... 73 DE MIKE

------------------------------

Date: Fri, 1 Apr 1994 19:40:52 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!usenet.ins.cwru.edu!news.csuohio.edu!vmcms.csuohio.edu![e-mail]
Subject: Attic Dipole
To: [e-mail]

In article <[e-mail]>
[e-mail] (hamilton on BIX) writes:

>
>[e-mail] (Troyce) writes:
>
>>Living in a duplex, I can't put an outside antenna up, so I have been
>>considering designs involving hiding a dipole in the attic.  I have about
>>50 feet of length to work with.  Right now I am considering a trap dipole
>>for 10-80 meters, 82' long.  This would entail running 50 feet straight

I have 4 indoor hf antennas inthe rafters. You could make a good 20 meter dipol
e.
You may also want to condsider making a loading coil, using a piece of pcc pipe
as the core, for that 80 meter antenna.  I picked up an article in one of hte m
ags a year or 2 ago for an apartment 80 meter antenna. it uses one coil.
I made it first tested it in the shack, and it was pretty good. It is now up in
 the rafters and still performs.

3 years ago QST had an article on a portable back packers multiband dipole for
10-40 meters using 5 or 7 wire ribon cable. It works ok, and can be cut for the
 WARC bands too.

My current antenna project is a 80 or 160 meter coiled dipole. I intend to coil
 the wire around a 3 or 3 1/2" pvc pipe(s) and hang it in the rafters. Alternat
ively, I just bought 2 slinky's to try as well, although I have not calculated
their legnth yet.

Indoor antennas are fun to experiment with. They do not compare with and outdoo
r antenna, but that makes them no less fun.

Bob
kf8ph

------------------------------

Date: 2 Apr 94 21:58:04 GMT
From: dog.ee.lbl.gov!agate!news.Brown.EDU!noc.near.net!news.delphi.com![e-mail]
Subject: CQ Article on HS-100
To: [e-mail]

Here's a quote from W1ICP's review of the $290 HS-100 mobile antenna
in CQ, April '94 issue:  "In my long career of working with antennas
I have only seen a few that were completely tuned from the operating
position.  By tuned, I mean an antenna that is tuned to resonance so
that all reactance in the antenna feedpoint is cancelled out at the
antenna."

Doesn't the conjugate match provided by my antenna tuner cause
maximum power transfer and tune the antenna system to resonance "so
that all reactance in the antenna feedpoint is cancelled out at the
antenna", (assuming near lossless transmission lines).  The antenna
tuner does not change the SWR on the transmission line but it does
neutralize the reactance at the antenna feedpoint because the local
conjugate match at the antenna tuner is transformed all the way to
the antenna.  Anywhere you look, up and down the transmission line,
you see -jX one direction and +jX the other.  As Maxwell said,
"My Transmatch Really Does Tune My Antenna."

My $15 Radio Shack CB whip covers 20m-10m with an antenna tuner.

73, Cecil, [e-mail]


------------------------------

Date: 2 Apr 94 22:00:43 GMT
From: dog.ee.lbl.gov!agate!news.Brown.EDU!noc.near.net!news.delphi.com![e-mail]
Subject: CQ Article on TH11DX
To: [e-mail]

I'm looking at the review of the $1000 Hy-Gain TH11DX beam in the
April '94 CQ. My question is, why bother? Here's a comparison of
the published gains vs what ELNEC says about my $25 102 ft. CF Zepp,
30 ft. high.

Freq.            TH11DX Gain          CF Zepp Gain (ELNEC)

20m              8.6 dbi              6.8 dbi

17m              8.4 dbi              8.9 dbi

15m              8.1 dbi             10.9 dbi

12m              7.5 dbi              9.6 dbi

10m              9.2 dbi             10.1 dbi

My Zepp also works on 30m, 40m, and 75m and I don't need a tower or
rotor.

73, Cecil, [e-mail]

------------------------------

Date: 1 Apr 1994 21:38:08 -0800
From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!nic-nac.CSU.net!ctp.org![e-mail]
Subject: Discone vs 5/8 wave for 2m packet?
To: [e-mail]

[e-mail] (Bill Turner) writes:

> 2 meter packet and said something you may want to consider.  In his
> experience, most problems with connecting to the node are not caused by
> weak signals, but rather by multipathing.  If that's the problem, a
> higher gain omnidirectional antenna will most likely make it worse
> instead of better.  He recommended a beam.  In his own personal case, he

It's almost a choice of two evils: struggle with the multipath and wait
for a better time of day for a connection or add to the congestion on the
packet channel by creating a "hidden terminal" to other stations on the
same frequency, which the beam will do.

--
Gary T. Lau
Internet: [e-mail] or [e-mail]
Amateur : N6MMM @ N0ARY.#NOCAL.USA.NOAM
"I don't think the California State University or Lotus cc:Mail wants me
to speak for them!"

------------------------------

Date: 1 Apr 1994 20:15:09 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!usenet.ins.cwru.edu!eff!news.kei.com!ssd.intel.com!chnews!scorpion.intel.com![e-mail]
Subject: How to base-feed half-wave vertical?
To: [e-mail]

In article <1994Apr1.101526.1@tntvax>,
Richard Steck, 312-630-6622 <[e-mail]> wrote:
>I'm looking for advice on the best way to match coax to the bottom of a
>half-wave vertical.  Cushcraft does this for the multi-band R-5 with some type
>of a proprietary network consisting of toroids, etc.  I only want to match a
>simple 20m half-wave vertical.  I'd prefer not to do the match with a "J" type
>of feed.  I'd prefer some type of a matching network.

An old-fashioned way to do this was with a parallel tuned circuit
between the end of the antenna and a (small) ground plane.  RF
was coupled to the tuned circuit with small adjustable link or
tapped up a few turns on the coil.  Kind of like this (hokey ascii graphics):


                    \|/  1/2 wavelength antenna
                     |
                     |
                     |
             +-------+-------+
             | _             |
             | /|             }  inductor
           ___/_  tuning      }
           _____  capacitor   }
            /|                }<-------
           / |                }         Feedline
             |               |
             +-------+-------+<--------
                     |
                     |
                   _____ Ground Plane
                    ___
                     _

>Please answer direct to:

>Richard Steck, W9RS
>Internet address:   [e-mail]
>Phone:  [phone]

Sorry, this was too good for E-Mail alone, although I'll send it to
you direct.

+-------------------------+--------------------------------------------------+
| Jim Bromley W5GYJ       |                                                  |
| Intel Corp. m/s C11-91  |        This message transmitted with             |
| 5000 W. Chandler Blvd.  |           100% recycled electrons.               |
| Chandler,AZ 85226       |                                                  |
| tel: [phone]       | Internet: [e-mail]              |
+-------------------------+--------------------------------------------------+

------------------------------

Date: Fri, 1 Apr 1994 19:25:52 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!csulb.edu!csus.edu!netcom.com![e-mail]
Subject: Super-conducting antenna (LONG)
To: [e-mail]

I recently received a letter from an old friend, Joe Speroni AH0A/7J1AAA,
who has been living and working in Japan for many years.  He is also the
author of the well-known MORSE ACADEMY software for teaching Morse Code.
Anyway, it was such an exciting letter that I thought it would be of
interest to others here on "the Net".

Dear Sandy:

I had promised a series of articles on Japanese amateur radio, but
there is something so exciting I just have to take a break and tell
you about it.

It all started with the work that Ed Coan (AH6MI/7J1AAE) did on
antenna pattern plotting using his personal computer.  The circular,
and even backward antenna patterns of some of our local TIARA
club embers brought home the point that what a good station needs is
a good antenna.  Ed's antenna looks great and the results verify it.
He works regular schedules into Colorado and Maine, just like sunspots
don't mean anything.  My mini-beam just could not compare.

Well, I got to thinking about what we apartment dwellers could do
and realized that space is THE problem.  How do you fit a full-sized
beam on a balcony?  Loading coils are the answer and the problem
at the same time -- the antenna radiation resistance drops as
reactance is substituted for length. High current loops develop
and the power is dissipated in the antenna instead of being radiated.
If only the antenna didn't dissipate the power.  Hmmmmmm....let's
see, P=E*E*R; if R were 0 then......

------------------------------

Date: 2 Apr 1994 09:37:39 -0500
From: ihnp4.ucsd.edu!library.ucla.edu!europa.eng.gtefsd.com!darwin.sura.net!news-feed-2.peachnet.edu!st6000.sct.edu![e-mail]
Subject: Super-conducting antenna (LONG)
To: [e-mail]

Someone please tell me this story is fiction....

I was going along with it until the ionized beam blew out the wall..

73
Matt Smith
KD4HME

--
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------------------------------

Date: (null)
From: (null)
The first test didn't go too well.  I connected the TS-930 to the
super-conducting wafer antenna and tuned it for 10 meters. At room
temperature, we couldn't hear anything.  Using a heat pump, the lab
technicians started lowering the antenna's temperature toward the
super-conducting region.  I was really impressed by how small the
equipment is, and started thinking it might all fit in the shack.
Just then, the TS-930 froze solid, which had a negative effect on
its operating characteristics.  This wouldn't be so easy after all,
the coax connection would need some study!

We reworked the wafers to put inductive coupling on them, but I could
find no way to efficiently couple to it from the conducting ceramic
material that passed RF but not heat.  Probably, something that
Kyocera invented just for this use.  I sent the TS-940 to the ham
shop in Akihabara and asked them to touch it up for me.  Suzuki-san
(service manager at the ham shop) asked exactly how the paint had
been peeled off around the coax connector -- lightning maybe?  No,
I assured him -- just low temperature exposure, without saying how low
the temperatures were. The project had to stay secret and besides,
Suzuki-san can repair anything!

Since it looked like it might be a while before the TS-930 would be
repaired, I brought out my TS-940.  I had already placed an order
for the Yaesu FT-1000 anyway.  After verifying that in the super-
conducting range the antenna was resonant on 10 meters, we connected
the TS-940. The ceramic material worked and the rig operated well
even as we began the cooling cycle.  The band seemed dead even
with the antenna at -150 degrees C.  It took another 10 minutes
to get to the super-conducting range -- then the TS-940 blew up.
It seems our antenna had a bit more gain than the TS-940 front-end
could take. Later, with 100 dB of attenuation, measurements showed
5 volts coming out of the coax.  A little hard to believe, but then
what do I know about cryogenic LSI antenna technology?!

The TS-940 was also returned to Suzuki-san, but this time he frowned
a bit -- the front-end board did look like it had been hit by
lightning.  Not to worry, Suzuki-san can repair anything!

The FT-1000 arrived just in time to be able to continue the experiments.
We built a QSK attenuator to protect the receiver and with the LSI
wafer antenna still inside the lab, decided to try to make a contact
on 10 meters. Boy, what a shock when we got it working.  The first thing
we heard was a couple of W2's talking locally on 10 meters and that was
with 80 dB of attenuation.  We had the antenna array on a rotatable
mount; I moved it about 1 degree and the W2's disappeared.
What beam width! We tuned them in again, and they were just about to
sign off, so we thought we would try to work them.  The rig was tuned
up at 50 watts on a dummy load; we switched in the wafer antenna and
gave N2BA a call.  The noise was unbelievable -- an ionized ray shot
out from the antenna and hit the wall of the building. Before we knocked
a hole in the band, we took out a piece of the lab wall!  Ever wonder
what an antenna pattern looks like in three dimensions?  There was a
small round hole in the wall of the lab -- about 1 cm in circumference.
We cut power quickly.  N2BA came back on frequency a few minutes
later and said he was using his back-up rig; something had taken his
main rig off the air.  For some reason, the station he was talking to
never came back, and so we decided not to transmit again until we knew
for sure what was going on.

As near as we can tell, the antenna array has 120 dB gain over a dipole,
but with a beamwidth of 0.75 degrees using the 60 dB points.  With
50 watts output, the effective radiated power is 55 quadrillion watts
at the center of the beam (5.5 with 13 zeroes). As soon as the
University realized what we had built, the entire project was taken
away from us and turned over to the Japanese Self-Defense Forces.
Amateur radio "tinkering" has contribute to something, but I am not
exactly sure what.  I haven't the slightest idea what was in those
wafers or how to explain how to build another set.  But what I'd give
to use a smaller set in the next CQ World Wide Contest!  Do you think
someone may be interested in this idea for Star Wars/SDI??

A few months later, the University contacted all of us and asked
just how close we had been to the antenna when operating. As best as
I can figure, we were in the null behind the array.  From what has been
said so far, it looks like a secondary use for our antenna may be as a
mass sterilizer, but confirmation will have to await the results of
the medical tests.  If our antenna ever hits the market, it looks
like remote operation would be desirable.

As I am writing this, I have been informed that Suzuki-san can't fix
everything after all.  He's written off the 930 and 940, and I just
found out that before the university terminated the project, they
tried one more time with my FT-1000, but without the 100 dB attenuator
to protect the receiver. It's front-end now matches the 940's and it
looks like it will be awhile before I am on the air again.  Maybe
Yaesu will announce some new models soon.

Best 73, Joe Speroni AH0A/7J1AAA, ex-Chief Engineer - TIARA
1 April 1994

This story has been reprinted and edited from the April 1992 issue of
the Tokyo International Amateur Radio Association's newsletter.
Permission is granted to reprint the material provided credit is
given to both TIARA NEWS and the author - Joe Speroni, AH0A/7J1AAA.

Actually, Joe originally wrote the above back in 1985 and it has been
updated by others since.  Hope you enjoyed it.
73 de Sandy WA6BXH/7J1ABV  [e-mail]       1 April 1994

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End of Ham-Ant Digest V94 #89
******************************