On Sun, 27 Apr 1997 07:10:29 -0600 "David McPhie" <K7SX@worldnet.att.net>
writes:
>What is considered optimum height above ground for a tribander? I
>know it
>is affected by surrounding terrain, but assuming flat level
>surroundings,
>and that the antenna will see the ground as ground, and not some
>rooftop,
>whats the best height?
>
> Is there any consensus on this, Ive heard 80 ft , 105
>ft, and just plain
>the higher the better.
>
> It seems to me that there must be sone "node" height that has
>demonstrated itself as beeing the most desireable within practicle
>limits.
>
>
>Dave McPhie K7SX [doing alright with a 50 ft tower, but always
>dreaming]
It depends on what skip distances are important to you. I would
suggest that you get a copy of N6BV's YTAD program, which is
available on the Internet, probably from the ARRL file server.
The program includes statistical files of signal arrival angle
for various DX paths. The program is a lot of fun to experiment
with.
50' is a pretty good height. Any higher than that and your
signal strength rapidly starts to decrease at the shortest
F-hops on 10 meters. In my case, it's important for me to
be loud in East Texas on 10 meters in domestic contests, so
I don't want that antenna any higher than 50'.
When you elevate a single tribander,
keep in mind that you get small gains at the low angles, but
really get killed at the high angles. If you are interested
primarily in DX, you can gain about 2dB at low angles on all
3 bands by going from 50 to 70'. You can gain another 2 dB on all
3 bands by going from 70 to 100'. You can gain another 2-3
dB on all 3 bands by stacking two tribanders at 50/100', which
also gives you the advantage of covering the high angles with
just the lower antenna.
Dave Hachadorian, K6LL
k6ll@juno.com
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