Hi Al,
As it happens, W6GJB and I are building a custom 80M vertical for FD use
on a mountaintop. As part of the design process, I've compared it to an
inverted Vee at the height where we could rig it without trees. The
model, of course, is for "flatland," and while HFTA can tell us how
being on that mountain affected the horizontally polarized inverted Vee,
we have no comparable modeling for a vertically polarized antenna. So I
asked Dean Straw, N6BV, retired ARRL Antenna Book editor and author of
HFTA how he thought being on the mountain might affect the vertical. His
answer was "I don't have a guess."
Our vertical will be built from that modular army-surplus mast that
comes in 4 ft sections that fit together with a 40 ft telescoping tube
mounted to the top, with a wire taped to it. We will feed it as a
vertical dipole, and there will be loading both at the bottom and top.
Not at all suitable for backpacking. :)
73, Jim K9YC
On Mon,7/20/2015 9:58 AM, Al Lorona wrote:
[I've re-named this thread. Was 'Miniature self-supporting HF Antennas'.]
When the ground is perfect, that's the best case for a vertical antenna. If the
ground becomes worse than ideal, then the losses increase and performance is
not as good and the pattern changes: less radiation to the horizon and higher
takeoff angle.
But then, if the ground continues to get worse -- let it become the worst case,
an insulator with zero conductivity-- don't the losses go to zero again? And
does the pattern go to more like an isotropic, or ...??? If the antenna does
look more like it's in free space, then this would support the statement that
there's radiation below the horizon from a vertical on a mountaintop.
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