Bill writes:
> The gist of the article was four elevated radials over average
> ground at 65 feet played just about the same as a 60 radial buried
> system. I don't have the particulars and my
That's about right for an 80 meter system.
The N7CL work that N4HY and N2EA reference indicates that elevating
the "ground plane" 1/4 wave above ground gets the coupling into the
soil down to insignificant levels (3/8 wave to immeasurable). At
heights approaching 1/4 wave, one could reasonably expect free
space performance out of a ground plane antenna if the feedline is
properly decoupled. N7CL's work is well worth reading ... it was
done for the military (if I recall correctly) and his summaries on
the reflector was the highlights of a very large study.
The real "take away" of Eric's work is to validate work by W8JI,
ON4UN and others that elevated radials at low heights (certainly
less than 1/8 wave) require a good in or on ground system for
best performance. For example, ON4UN used a single elevated radial
on each verticals in one of his early 80 meter 4-square arrays but
that array sat directly over his 160 meter ground system which
consisted of 250 radials from 65 to 200 feet long.
73,
... Joe, W4TV
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|