Hi Doug ,
Like so many things related to antenna installations, side by side
comparisons are usually impossible. Without the ability to do meaningful
measurements, it is also unlikely that one can capture all the unknowns
that can add up to a large effect. I could do only relative field strength
measurements in the near field at the time, which appeared to be pretty
similar. I could also get a useful inference of the ground loss component,
which was also similar between the two sites, with the new site being a
little better. All the equipment and feed lines were exactly the
same--just transplanted. One site is clearly better than the other, by
whatever mechanisms make one site better than another. Personally, I
suspect that several factors were in play, and I will never know all the
factors. BTW, I am RF engineer by profession and I know very well that a
great many factors influence the field strength of a transmitting antenna
system. I wish that I knew the full story of the two installations, but I
do not. Wet wood is lossy and I know that I did a certain amount of
heating of the trees. RF wood dryers work by RF heating after all. Was my
wood heating enough to give the observed differences? Probably not. Did
my country total on 160M jump from 56 in 2-years of trying to something
past 150 the first winter after the move? Yes it certainly did. That much
can be quantified. The rest is educated guessing.
I have decided that the next time that I am in that area, I am going to
snag a piece of pitch pine and spend some lab time and characterize it. It
is a very resinous wood that may have interesting RF properties. I had
a hundred or more pitch pine in the near field of my low band vertical and
and many were upwards of twice its height and 20" thick. They are not
transparent to RF, but to what extent they are sticky vertical RF absorbers
is currently unknown.
73,
Steve, AB4I
On Tuesday, August 6, 2013, Doug Renwick wrote:
> The only way to say which location is better is to do a side by side
> comparison which didn't happen. You are making assumptions which may be
> wrong or may be right. Blaming it on trees is a guess. There are many
> other factors to consider.
> Doug
>
> -----Original Message-----
>
> It's hard to quantify all that, but operationally
> there is no question which installation gave the better results on
> Topband, by a fair margin.
> 73,
> Steve, AB4I
>
>
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Topband Reflector
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