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Re: VLF: Ground loop improvements and test carrier...

To: [email protected]
Subject: Re: VLF: Ground loop improvements and test carrier...
From: DK7FC <[email protected]>
Date: Wed, 03 Apr 2019 20:10:52 +0200
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Hello Paul,

Thank you. Interesting. For you the difference is 2.8 dB. But the loop points almost fully into your direction. The angle turned from 6 deg to 3 deg, ie. a theoretical gain of G = 20 lg(cos3/cos6) = 0.04 dB. But i see, 1.3/1.07 < 1130/900, but not much! And maybe the QRN increased during that time.
Yes, a constant return depth of the current was assumed. So, for your
direction i would assume something like G = 20 lg(1130/900) = 1.98 dB.
So the 2.8 dB is a good value! The propagation path should have changed
mch during that short time.
Amplitudes:
900m: E-field: 5.329e-07   H-field: 2.081e-06
1130m: E-field: 8.853e-07   H-field: 2.995e-06
...calculated using vtwspec.

+66% in the E field and +44% in the H-field.

73, Stefan




Am 03.04.2019 18:00, schrieb Paul Nicholson:
Stefan wrote:

> A carrier transmission was done at 8270.1 Hz, using an antenna
> current of 2 A on both antennas.

Received here -

 900m Ant:  T2019-03-31_13:58,+10m: 1.07fT S/N -10.4dB/1Hz

 1130m Ant: T2019-03-31_14:12,+10m: 1.30fT S/N -7.6dB/1Hz

The signal strength hasn't increased as much as the area has
increased.  So maybe the ground return current has remained
at the same depth.  Then the signal would increase as by 1130/900
which is close to what I see here.

Can you compare amplitude and not S/N?

--
Paul Nicholson
--





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