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Message-ID: <3.0.1.16.20010516103336.2b5f0e90@mail.cc.kuleuven.ac.be>
Date: Wed, 16 May 2001 10:33:36
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
Subject: Re: SV: LF: SV: Re. T/A tests.
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Hello group,

I am not sure that propagation on 137kHz is much correlated to 1.8 or 3.5MHz.
On those bands (160m and 80m) DX propagation is mainly via reflection at
the F2 layer and the signals are attenuated by the D (and eventually E)
layer. During solar minimum the ionisation of the D and E layer is very
weak while the F2 layer ionisation remains strong enough for these low
frequencies.
When I understand some articles about propagation on LF well, DX
propagation is via E layer reflection (in some seldom cases even D-layer
reflection). This would explain that QSO's up to 2000km (1 hop e-layer
reflection) are made with rather low ERP (few 10mW) while transatlantic
propagation (2 hops or more) require at least a few 100mW.
Question is : will the E layer ionisation be strong enough at soloar minimum ?
The answer will be known in a few years ...

73, Rik  ON7YD

At 11:05 15/05/01 -0700, you wrote:
>
>Hi Chris,
>Terman's graphs show that T/A sig levels are strongest during peaks of the
>solar cycle. Whereas the correlation that Laurie described is T/A success
>when sunspot numbers are low.
>My guess is that both are probably true, i.e. on average T/A signal levels
>are better during the active part of the cycle, but conversely weak signals
>are more likely to be disrupted during the active part.
>We will probably find that at the low point of the cycle chances of getting
>across are worse but consistently worse, if you follow me.
>73, John
>
>
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