[TowerTalk] Takeoff angle-new perspective

[Pete Smith]

At 06:50 PM 12/20/00 -0600, Tom Hellem wrote:
...
>
>I think a large percentage of hams have neither the pocketbook nor the real
>estate to erect multiple towers and stacked yagis. Many of us have to settle
>for one tower of modest height with a tribander, and we are pretty much
>resigned to the fact that we are probably not going to make it into the
>record books in CQWW. But, being of a somewhat competetive nature, we think
>that we have at least a chance of making a showing in the stateside contests
>like NAQP and SS.
>
>So the question becomes this: What would be the optimum height for say a 3
>element triband beam for stateside contesting use? Say up to a maximum
>height of 70 feet or so, as that would be about tops for Rohn 25 with 2 sets
>of guys, and would be able to fit on an average sized lot.
>
>I would be willing to bet there are thousands of us out here who would be
>very interested to see some input on this question.

Whether your objective is stateside contesting or DX contesting, and
regardless of the constraints on your antenna possibilities, you need to do
analysis that is specific to your situation.  That means that you need to
know the takeoff angles from your qth to the areas of interest, and you
need to know how your local terrain will affect the takeoff angle from
antennas you might choose to put up.  A 50 foot high tribander could be far
too high for domestic contesting, if it was on top of a conical hill with a
relatively steep slope.  One 200 feet high might not be much use if it
faced a rim of close by hills in all directions.  50 feet might be just
about right if your QTH was flat.

The tools you need are VOACAP, for propagation angle predictions, and YT,
for assessing the effects of terrain on your antenna's pattern.  In
general, I think you need to be strong into the major ham population
centers of the country, which means the Eastern seaboard, the west coast
and the South central states.  If you live in one of those areas, you may
also want low "cloud-burner" antennas, particularly on the low bands.  


73, Pete N4ZR

Contesting is ... Extreme Radio

The World Contest Station Database 
is back up and running at
http://www.qsl.net/n4zr 



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