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[antennaware] Radial Study

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Subject: [antennaware] Radial Study
From: (Gary Breed)
Date: Wed, 23 Sep 1998 08:52:51 -0400
Hi Jan,

It's going to be weeks or even a couple months before I have
time to attack a follow-up to the radial study I reported.

To answer your question on 1/2 or 5/8 radials, they are generally
NOT effective with a 1/4 wave radiator.  The feedpoint of a 1/4
wave vertical is a low impedance, while the ends of 1/2 wave wires
are high impedance points.  Longer radials like 3/4 wave
will have a lower impedance that is more compatible.

There are some antenna specialists who believe that long elevated 
radials experience greater ground losses, as they have a greater 
length where they interact with the lossy ground below them.  I don't
have enough data to confirm that possibility.  I have also heard that
extra long BURIED radials (more than 1/2 wave in length) provide an
improvement in radiated efficiency -- I know of at least one ham
with an 80-meter vertical who added several 2-wavelength radials 
toward Europe and swears that it made a significant improvement.

A typical approach for a 80/160 installation would be to have
radials of two lengths in the system -- a set of 1/4 wave radials
for each band.

Have fun,

Gary K9AY


Would you be willing to rerun the vertical antenna model with elevated
radials and make the radials longer?  I would be interested in
5/8-wave and 1/2 wave.  I have some possibilities of running verticals
for both 80 and 160, and that is why the 1/2 wave question arises.
The 5/8 simply represents the difficulty in measuring radials.  Does
it matter as long as I make them at least 1/4-wavelength?

Jan, KX2A

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