[TowerTalk] TowerTalk Digest, Vol 50, Issue 56

[Jim Lux]

At 06:43 AM 2/24/2007, Jay Terleski wrote:
>The best way to answer these questions is to get a copy of HFTA,
>which comes with the ARRL Antenna book. It lets you model the pattern
>of stacked antennas, varying spacing, etc., and factoring in your
>terrain, as well.  You just select the kind of antenna (e.g. 5
>element beam), and the heights and frequencies, and it plots out
>patterns (using generic patterns based on nominal performing antennas).
>
>
>Unless Dean Straw has changed HFTA it doesn't stack the antenna
>correctly. It alway assumes max stack gain. It's purpose is primarily
>for take off angle estimates.

Well not precisely max gain.. unless you fool with the phases of the 
antennas. I think it assumes no interaction between antennas, and 
models them as idealized patterns, but you're right.. it's primary 
value is to find nulls or generalized takeoff angles.