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Old September 30th 06, 10:39 PM posted to rec.radio.amateur.antenna
Steve Reinhardt Steve Reinhardt is offline
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First recorded activity by RadioBanter: Sep 2006
Posts: 13
Default 20 M vertical ground plane antenna performance?

I'm looking at another antenna for 20M. I've got a partially folded
indoor attic antenna which gets out fairly well, but it certainly is
directional.
The ARRL handbook has had this design in it since they invented
radio. It's often used at VHF, but seems a good candidate for this QTH.
It's a 1/4 wave element over 4 1/4 wave radials at 45 degrees off
horizontal, drooping to earth. My installation would be at ground level,
with the base of the radiating element about 12.5 feet of the earth.
Mechanically, it would be easy to put together, but I hate to waste
the time if it's known to be a poor performer. I tried to use the EZNEC
4 demo, but 55 segments aren't enough to create a reasonable model of
the physical layout, and I'm not smart enough to try a simplification.
So, has anyone done an analysis of this antenna? Would the
performance be similar to a low mounted vertical dipole, or would the 4
radials offer a bit better performance so close to earth?
If there's an literature I missed, please point me toward it. Most of
the antenna manufacturers refer to regular flat, on the ground radial
systems, and except for some CB literature which has no technical basis
for its recommendations, there's not any analytical data I can find. The
best thing I found was at web.wt.net/~nm5k/acompari.htm for 10m
applications, at 40 ft elevation.

73,
W1KF
Steve