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

[DK7FC <selberdenken@posteo.de>]

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
> --