[TowerTalk] a fancier hfta

[Steve, W3AHL]

HFTA does allow selecting 9 combinations of soil conductivity/dielectric values, but the impact on the gain pattern is relatively small (0.5-1 dB) in most of the cases I've tried.

Steve, W3AHL
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Date: Sun, 25 Apr 2010 16:20:32 -0700
From: jimlux <jimlux at earthlink.net>
Subject: [TowerTalk] a fancier hfta
To: Towertalk Reflector <towertalk at contesting.com>

For those interested in a more sophisticated approach, one starting
point is the 1994 paper by Breakall, et al.

J.K. Breakall, J.S. Young, G.H. Hagn, R.W. Adler, D.L. Faust, D.H.
Werner, "The Modeling and Measurement of HF Antenna Skywave Radiation
Patterns in Irregular Terrain", IEEE Trans. Ant. Prop. V42, #7, July
1994, pp936-945



Abstract is below..

Basically they used GTD with the current distribution in the antenna as 
the source.  They also (as expected) found that for horizontal 
polarization, you can just assume that the terrain is perfectly 
conducting (which I believe HFTA does), while for vertical pol, you need 
to know what the dielectric properties are.

  ..snip..
Jim, W6RMK

..snip..