[TowerTalk] Not just what antenna, but how high and the QTH

Paul Christensen w9ac at arrl.net
Sun Apr 12 23:40:20 EDT 2015

> "Mike brings up an interesting point.  Yes, the antenna is  important, but
so is how high you put it up and the surrounding terrain.  I  can't stress
strongly enough how important it is to do HFTA, especially if you  live on
anything other than flat Florida terrain."

Even Florida has some siting opportunities that make HFTA worthwhile.  As 
K4XS, mentioned, using HFTA over long periods of time will make easier 
siting decisions.  The sites I have researched are either on geographic 
"knobs," like the W3CRA site in Canonsburg, PA, or sites along a river that 
meander in an arc toward the most desired directions.  Those sites often 
provide a moderate drop over a large azimuth arc, and that's what creates 
low, controlled take-off angles below 5 degrees.

The site we're finishing this month is located to the east and south of the 
St. Mary's River near Hilliard, FL.  By the HFTA computations, there's no 
viable height that can take the place of the sloping geography.  For 
example, into Oceana and JA on 40m, we would need to be more than 220 ft. 
above ground to equal 1-3 degree TOA performance at 140 ft over sloping 
terrain, looking to the west and north.   Sounds easy, but it isn’t.  It 
takes a lot of patience to find the right geography that works for a 
neighborhood installation or even an internet remote location.  Last year, I 
spent countless hours looking for remote sites with these geographic 
features that had access to AC power and high speed internet.    The list 
gets whittled down very fast.

One of the most interesting areas I've researched is Charleston, WV.  There 
are many locations in residential neighborhoods that offer superb geography 
for low TOA from antennas that need only be up 40 ft or less and at very low 
angles, will be competitive with tall stacks over flat terrain.  One example 
of this is the former site of Al Hix, W8AH.  One motorized tower to optimize 
height per band, and you're done -- at least if long-haul DX is your thing. 
There is one piece of property on a city lot at the end of a high cul-de-sac 
that according to HFTA, would produce extraordinary low TOA all the way down 
to 80m with low antenna heights in about a 300 degree arc - and do it with a 
smooth vertical profile.

Paul, W9AC 

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