HFTA results are depended on your local terrain. Not too useful for the
flatlanders, just start at one wavelength and go on up. For the ops with
an overly complex hill top the program's results get interesting and again
not too useful.
Somewhere in the middle ground the program does have value and I'm
one that can report good results from using it. I also have enough antennas
up now to verify some of the predictions made by that software as true.
I moved the contest station from Fairbanks to the Kenai and started
rebuilding on a hill top with steep, but mostly smooth, roll off to the
ocean. Dean, N6BV, flew up and did the tower/antenna layout for
me in one afternoon. By the way don't expect this service unless you
happen to be a double mult in the WW. Dean's also very quick with
the program, little hard to follow and he generated much better terrain
files then what I was using.
Most of the antenna heights seemed too low to me. One was a 20 meter
yagi at 45 feet to USA. I'm not a 45 feet yagi kind of guy. Never the less
N6TR, Log checking boss, K5KA, SS boss, K6AW, WPX boss, (again
the double mult thing), and I put up the towers. I did put the top guy at the
bottom of the top section just in case we needed to go higher.
Results, the low 20 meter yagi is often much louder then a yagi twice as
high. Often and by a lot. Enough to think the top antenna is broke. I have
seen the reverse to Europe where the low antenna seems "broke" and the
high antenna is really loud, all in the same morning. What I hear on the
radio is what I see looking at the HFTA plots for these two yagis.
HFTA shows the standard 30/60/90 stack for 15 during a good 15 meter
opening to USA that the top antenna will be too high and the bottom two
antennas will be better then the stack of three. I have seen this twice so far
which was enough to convince me to build a second stack of two 5/5
antennas using the 30/60 heights.
HFTA showed a single 20 meter antenna on the West edge of this hill at
60 feet would be as loud to Japan as the stack that is on the East edge.
Just to see for sure I put up an antenna at that height and location. The
stack was never better in the two weeks I tested this.
HFTA predicted that for Ten meters on this hill top edge a forth antenna
in my 4/4/4/4 stack was of little value so I built a 5/5/5 stack instead. I am
waiting to actually hear a signal on ten before we build the rest of the ten
meter systems.
HFTA predicts my 40 meter yagi's height of only 105 feet on the cliff edge
is an electrical height of 240 feet and nothing will be gained by going higher.
This seems to be a very good height if you use the "one CQ, big pile" rule.
I corrected my location in QRZ.com so anyone interested can search my
call and look at the hill top in Kenai, Alaska. Japan is West, Europe is
North and USA is East.
Your HFTA results may vary.
73 Rich KL7RA
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