[Amps] Terrain Mapping for EZNEC ( Again )

[Jim Brown]

On Sun,12/14/2014 12:59 PM, donroden at hiwaay.net wrote:
> Several months ago, someone recommended a mapping program that looked 
> at the near field ground around a tower to predict take-off angles and 
> ground reflection gains.

The only one I know about is HFTA (High Frequency Terrain Analysis) 
written by N6BV, and distributed the the CD with the ARRL Antenna Book. 
It predicts the interaction of HORIZONTALLY polarized waves with 
terrain. It has a learning curve, it can be tricky downloading the 
needed terrain data from government websites (but it's free), and it can 
take a lot of work (I spent months) to get a useful set of predictions 
for all the bands and for several possible antenna sites, but many of us 
here in the interesting terrain that California provides swear by it (me 
included).

Dean, N6BV, did a very good WebEx tutorial several years ago, that is, I 
believe, still on the PVRC website. Buy the ARRL Antenna Book, and study 
the parts of a chapter that explain the concepts and how the program 
works. Then watch the WebEx.

Note that this program does NOT work for vertically polarized waves 
because they interact very differently with the earth. I asked Dean 
about the practicality of writing something for verticals, and he 
indicated that a major roadblock is the availability of sufficiently 
detailed data on soil conditions. Turns out that data is useful for 
mining, so you gotsa pay for it, and it ain't cheap.

73, Jim K9YC