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LF: RE: CFH plots

To: [email protected]
Subject: LF: RE: CFH plots
From: "M. Sanders \(PA3BSH\)" <[email protected]>
Date: Sun, 5 Mar 2000 12:40:18 +0100
Importance: Normal
In-reply-to: <[email protected]>
Reply-to: [email protected]
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Hi All,

You can download the software at:

Thanks are due to ON5OO for writing the monitoring software. Does anyone
have a good copy of the original EXE file? The one I posted on my site
is corrupt and I deleted all other copies - doh!

Mike, G3XDV

Congratulatins on the results on 73kHz! The flares seem to have a more or
less similar effect on de D-layer as was seen during the '99 eclipse. I am
convinced now there are two effects that work independently.

1) Reflection against the bottom of the D-layer. The D-layer lowers when the
intensity of the radiation increases. This gives an increase in signal
strength because the reflection improves when the angle of indecense

2) Total internal refraction of LF signals in the D-layer. The ionisation in
the D-layer increases and so the signals passing through attennuate. This
causes a decrease in signal strength.

Both effects are combined in the reflection coefficient formula for 'sky
wave' propagation. Observations during the eclipse have shown there is a
time difference between the effects 1) and 2).  The height appears to change
rapidly and the ionisation process appears to take some time before
propagation is affected.

This time difference causes both the significant increase and decrease of
the signals we observe (and we can use the increase for DX communications of

Best 73's and good luck on lf,

Michael Sanders, PA3BSH

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