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Richard Clark · February 14th 09, 01:32 AM posted to rec.radio.amateur.antenna

On Fri, 13 Feb 2009 16:46:29 -0800 (PST),
wrote:

What I'm after here with this project is better low angle radiation
for the purpose of working DX. My present 40 meter antenna is a dipole
that is only about 20 feet of the ground. Not ideal as I'm sure you
guys well know.

Hi Michael,

Your goal is admirable. Your goal shares the same aspiration of many
others who select a vertical antenna. We hear this goal quite often
as a reason for its choice. Unfortunately....

The greatest indicator of success in achieving low angle radiation for
a vertical antenna is actually found many wavelengths away from your
antenna - in the quality of the soil surrounding it at this distance.
The quality can be roughly determined by general descriptive
categories (like living next to a swamp or the ocean); or by reviewing
the FFC's ground charts.

Significant elevation of a vertical can reduce ground loss through
distance. It has been reported that the need for large numbers of
radials declines with this distance. You might think of hiking your
vertical higher. This reduction of loss translates into better
performance at lower angles, but it is not in its own right a solution
to better low angle performance as may be expected from simple
diagrams found in elementary discussion.

The best you can hope for is keeping both antennas, and trading from
one to the other for their diversity (when one won't work, the other
might). It serves no purpose to launch your RF off at 1 degree above
the horizon when it would only land in the Atlantic, skip a continent,
and land in the Indian Ocean. Propagation conditions will always
trump intention.

73's
Richard Clark, KB7QHC

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