Date: Mon, 22 Feb 2010 16:27:13 +0100
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
From: Rik Strobbe <rik.strobbe@fys.kuleuven.be>
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Subject: Re: LF: VLF_8.79 kHz
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>With the ground wave, one could reach the whole europe, i expect. 
>But that are dreams...
>
>Stefan/DK7FC

Stefan,

I you can manage to produce a significant ground wave signal the real 
advantage of 9kHz might be at distances beyond 1000km.
I played a little with GRNDWAV3 (written by G4FGQ) and the difference 
between 9kHz and 137kHz seems minimal below 500km (< 6dB) while it 
will be much more difficult to generate any ERP at 9kHz.

Just to give you an idea :
Assuming -60dB antenna efficiency (0.00001%, that is the lowest value 
accepted) at both TX and RX side, average terrain and 1kW TX power 
the RX voltage according to GRNDWAV3 is 50uV at 33km (1 wavelength), 
18uV at 100km, and 1.4uV at 1000km.
But I am afraid that -60dB it quite optimistic and that -80dB would 
be a more acceptable value, what would reduce the RX voltages to 
resp. 0.5uV (33km), 0.18uV (100km) and 0.014uV (1000km)

73, Rik  ON7YD - OR7T

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<blockquote type=cite class=cite cite="">With the ground wave, one could
reach the whole europe, i expect. But that are dreams...<br><br>
Stefan/DK7FC</blockquote><br>
Stefan,<br><br>
I you can manage to produce a significant ground wave signal the real
advantage of 9kHz might be at distances beyond 1000km.<br>
I played a little with GRNDWAV3 (written by G4FGQ) and the difference
between 9kHz and 137kHz seems minimal below 500km (&lt; 6dB) while it
will be much more difficult to generate any ERP at 9kHz.<br><br>
Just to give you an idea : <br>
Assuming -60dB antenna efficiency (0.00001%, that is the lowest value
accepted) at both TX and RX side, average terrain and 1kW TX power the RX
voltage according to GRNDWAV3 is 50uV at 33km (1 wavelength), 18uV at
100km, and 1.4uV at 1000km.<br>
But I am afraid that -60dB it quite optimistic and that -80dB would be a
more acceptable value, what would reduce the RX voltages to resp. 0.5uV
(33km), 0.18uV (100km) and 0.014uV (1000km)<br><br>
73, Rik&nbsp; ON7YD - OR7T <br>
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