Mike, others have given what I consider good advice on several of the points
you asked about. I'll take a crack at your question about Moxon's
counterpoise advice. I'm slowly going through Moxon's book. Its
fascinating reading, by the way, for those looking for new antenna ideas or
new ways of looking at old antennas. But his writing style isn't always
very clear and easy to comprehend. And some of his "contraptions" with
multiple feedlines coming into the shack seem overly complicated to me.
But, all in all, I still recommend the book.
His point about the conventional ground plane with 3 or 4 sloping
counterpoise wires goes as follows. The assumption that all 3 CP wires will
carry equal current is bogus. Since they all vary slightly in length or in
coupling to surrounding objects, their impedance as seen at the feedpoint
will also vary widely. The net result is that one of them will take a large
percentage of the current while the others will be mostly ineffectual, and
the hoped for symmetrical pattern will not in fact occur. To obtain the
desired symmetry, he suggests using CP wires cut to less than 1/4 WL (even
substantially less) and then putting an inductance between the common
feedpoint of the CP wires and the return side of the feedline. This
inductance is then adjusted to obtain resonance of the CP wires at the
operating frequency. This way, they will share the RF current much more
equally. I have not tried this approach, but it seems to make sense to me.
Another point he and others make, that I can confirm from experience, is
that 3 or 4 CP wires and a symmetrical pattern really aren't needed in
practice anyhow. I use a BuddiPole in a vertical arrangement with one
sloping CP wire per band and it works just fine and seems to work stations
in all directions without a problem. I don't have his book in front of me
right now, but somewhere in it is a nice table or graph that compares ground
plane performance vs. number of CP wires, and hardly anything is lost by
reducing the number.
73
... Craig AC0DS
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