Yes. Rick's study, using HFTA, takes terrain into account. I've done a
similar study using NEC, which assumes "flatland," and produces similar
results. BUT -- what HFTA tells you is unique to whatever terrain data
you give it. What Rick is describing is good for HIS QTH, but may not be
good for yours.
Here's are links to my study. The first is text format, the second are
slides for talks I've given at Pacificon and to several ham clubs.
http://k9yc.com/AntennaPlanning.pdf
http://k9yc.com/VertOrHorizontal-Slides.pdf
One thing that HFTA will tell you (correctly) is that if you're on a
hilltop, you don't need as much height as you would on "flatland." My
dipoles for 80 and 40M (two fans at right angles to each other) are at
140 ft, and they really play well. Likewise, a pair for 30M at 100 ft
work great.
73, Jim K9YC
On Tue,6/21/2016 1:32 PM, Rick WA6NHC wrote:
Based on that review, with as little as 1/4 wavelength above dirt,
good things start to happen beyond NVIS (straight up) activity, the
takeoff angle falls. At ~3/8 wave, the radiation angle of a dipole
comes down remarkably, almost to the magic 2 deg level (best chance of
DX or longer openings). At about a half wave up, the advantage is
less for the extra height (less return on the 'investment'),
improvements came slower per altitude change. The same can be said of
beams but with the added gain (Yagi, enhanced dipoles). At another
point, the advantages start to reverse too. It was an interesting study.
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