Topband: What do you use as a "Run" antenna?
w8ji at contesting.com
Wed Feb 28 06:46:23 EST 2007
I never said it was a difference in absorption.
I said it was because noise levels and QRM levels are higher
at the dark location. The D layer attenuates the QRM and
noise at the daylight spot the same as it attenuates the
desired signal, but the guy listening at the dark location
has all that unattenuated noise and QRM from other
You are station B in daylight receiving station A who is in
darkness. At your location, station A is attenuated by the
daylight D layer the same as all the distant noise and QRM.
The fellow at station A (in darkness) is faced with noise
and QRM that is NOT attenuated from other directions, but
your signal from out of the daylight is.
That is what makes it easy in late daylight to hear distant
stations out of a dark area while they can't hear you.
For example during afternoon daylight my noise floor is
about 10dB or so less than at dark. I can hear Europeans
very well but there is little hope they can hear me. As it
gets dark, the noise and signals here go up together because
the D layer starts to fade, the noise in Europe doesn't get
any worse, and now when I call I'm ten dB stronger and they
can hear me.
The reverse effect occurs after my sunrise. I can hear west
coast stations very well even at 10-11 AM. When I call them,
they don't hear me nearly as well. This is because they have
all the darkness noise and QRM while the darkness QRM and
noise is attenuated here almost the same as their signals.
They don't lose S/N as fast here as I do there at my
A second factor is people aren't normally listening into
daylight as much as they are listening towards dark paths.
This is especially true in contests where there might be
hundreds of workable signals from the dark path while there
are only occasional signals from the daylight areas.
IMO that is what causes the frustration. I learned long ago
to not bother calling Europeans that are readable at 1-3PM
local here. They are closer to dark and have higher noise. I
am in daylight and have virtually no propagated or local
By the way, this noise problem in not escapable. Noise on
low bands always comes in from a great distance, even in
winter. The only exception is if you have dominant local
noise that masks distant noise. What we attribute to as "one
way propagation" is almost always the fact that noise level
is too high at one end of the path.
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