I received some nice mail and information from K9UWA regarding station
modelling. John has his entire station modelled and knows exactly what
kind of interaction he gets from his other antennas.
A new antenna that I am thinking about putting up has caused me to think
about the same thing at my place. I'm simply running out of room. So now
I'm in the process of modelling everything to see the interactions.
I was fortunate to have operated at two very good stations (N4RJ and
K4VX). One thing that was common at both stations was the lack of nearby
antennas. At N4RJ, Val had one band per tower. I now believe that this
was a large part of my success at this station. He didn't have any
"unkowns" screwing up the pattern of his antennas.
With the few towers I have modelled so far, it is interesting to see how a
nearby structure can totally screw up a great pattern from an optimized
antenna. I now have to wonder about these guys who stick up a ton of
antennas on one mast or tower.
We spend a lot of time modelling antennas in free space to eek out the
very last 1/10th of a DB. Then we take that antenna and stick it up in
the middle of an aluminum jungle. Not sure that makes much sense.
One thing I have learned is that my 4-square which surrounds a 115' Rohn
45 tower is definatley affected by the tower in the middle. The F/B goes
from a 25DB in the perfect model to 18DB or 19DB with the tower in the
center of the square. In my case, it's the only place I can put the
verticals. But it explains a few observations.
Has anyone else done any complex station modelling to see the affects of
nearby antennas?
73
Bill
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