Using tools like TA has anyone compared the effects of
very close-in terrain to distant horizon clutter. Specifically
which would be more detrimental to take-off angle, an HF
antenna mounted directly over a gentle 3 degree upward
slope for a mile or two, or that same antenna mounted over
flat terrain which looks at a range of +3 degree high mountains
say 30 miles off in the distance? Simplistically, it seems
that these two cases would be about equal in terms of their
impact on TOA, but the high mountains might provide
some interesting diffraction effects, whereas the flat local
slope would probably just skew the antenna elevation
pattern up +3 degrees.
I was looking at a site (rural setting with a very low noise
floor) that I was considering for portable operation that
exhibits a gentle upward slope toward the SW with a
nearby visual horizon (+0.5 miles away) that is approximately
concident with the mountains that are ~30 miles away. Both
the close-in and far distance visual horizons sit at about 2.5
degrees elevation (e.g. you can see the mountain ridges
peaking just slightly above the close-in visual horizon). In
other directions the terrain is very favorable. Any thoughts
on this?
Thanks,
Mike, W4EF..........................................
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See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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