[TowerTalk] RE: 80 meter 4 square array notes from N0AH

[Dick Green]

> - With sloping ground, is it more important that the feedpoints be in the
> same plane rather than follow the contour of the land? I went to an
elevated
> feedpoint so that all the feedpoints are in the same plane. This works out
> that one vertical's feedpoint is 7' above the ground while the other 3 are
> 14' above the ground. Or is the difference so small that I should just
feed
> all of them at the ground level?

Jim at Comtek recommends that all of the feedpoints be at the same level,
but I'm not sure what happens if you don't do that. Presumably the pattern
would be affected, but I don't know why that would be. After all, the
difference in height is normally only a small fraction of a wavelength.
Perhaps it's more of a factor for elevated radial systems.

Three of my 40M 4-square elements (NE, SW, NW) are on a relatively flat
portion of a steep hill. The feedpoints on these three elements are pretty
close in height, probably less than a foot of difference between them. But
the fourth element (SE) is up the hill a bit, and the feedpoint is anywhere
from 2-3 feet higher than the other three elements. I haven't been able to
detect any difference in performance between this direction and the other
three. I opted not to equalize the feedpoint heights because that would have
complicated the mounting method and I was concerned that different heights
would result in somewhat different feedpoint impedances. Several other
4-square owners told me that they hadn't done it either. YMMV.

73, Dick WC1M



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