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LF: Sun spots and Terman

To: "LF-Group" <[email protected]>
Subject: LF: Sun spots and Terman
From: "Alan Melia" <[email protected]>
Date: Tue, 15 May 2001 10:56:39 +0100
Reply-to: [email protected]
Sender: <[email protected]>
Hi all, this is a interesting LF going to get better, or worse,
as we go down into the next solar minimum ??
The problem with Terman's graphs are that they are 'averages' and looked at
in light of the greater detail in some of the pre-war papers on LF
propagation they only tell part of the story. Also they are aimed at
determining useful service area for broadcast stations and reliable point to
point comms. Amateur communication does not exist on 'averages' but
generally survives on peaks and rarer events. It seems true that the peak
strengths of signals are higher in disturbed conditions but the dips are
also lower, and there are prolonged periods of severe absorption.  It is not
clear what his averages refer to, how long the signals are high, and whether
there are deep fades as well.

I suspect that the 'quiet' sun conditions of a solar minimum will not be as
good as conditions when a geomagnetic disturbance is just decaying away.
Fortunately the sun continues to produce some geomagnetic events even in
quiet years. Quieter periods around the 11-year maximum may well turnout to
be the best times for extreme DX on LF.

Top band experience is interesting as some of the effects are common, but
160m propagates by the F-layer, whereas, as far as I can be sure, 136 kHz
propages by the D-layer and at most the lowest regions of the E-layer. There
is a lot to be learned (or re-discovered) over the next 11 years !! I do
hope some s/w for watching Loran signals becomes available as this would be
a powerful tool for systematic monitoring.

Cheer sde Alan G3NYK
[email protected]

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