Conditions on the first pass on 432 here were what I call good , polarisation was sharply
defined, but the fading was very long with shortish strong peaks sometimes as much as 40
seconds apart and long periods of weaker signal. It was not a polarisation effect because
I was able to check this with the fully rotatable feed. In the fades the signal remained
low despite rotating the feed. This is a similar effect to that which was observed last
year ( 2007) and in October 2008 but then the effect was only at moonrise plus a few
hours. This time it seemed to persist for much longer, up to 6 hours.
I dont recall encountering this before and years ago there was more 432 activity so one
would expect to have seen it more easily.
By contrast on the second pass here, from moonrise on, signals were definitely weaker...
because the polarisation was badly spread with little change over large rotation angles...
The same fading effect was still present but much less marked.
Bill W4TJ and Doug VK3UM have both commented on " difficult / unusual"
conditions. Does anyone have any rational explanations for this?
As I see it, there are three effects, Faraday rotation, Absorbtion and Libration, all
with different periodicity. I think I can largely eliminate polarisation. Can it be that
the libration and absorbtion rates of change are similar at this period of the solar cycle
for some reason and so we are seeing the interactive effect of two slowly changing
periods?
I gather we are in the quietest period of sun activity since before amateur EME began,
could this be significant?
73 Peter G3LTF
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