Congratulations Chris! I will have to add this new UK VLF record to my sub-9kHz webpage. If Jim can copy then I should be able to as well with a better set-up. So pleased for you. Brilliant.

73s
Roger G3XBM

Sent from my iPod Touch 4g

On 31 Dec 2010, at 17:45, "James Moritz" <[email protected]> wrote:

> Dear Chris, LF Group,
>
> The signal disappeared some time around 1520utc - the complete trace is shown in the attachment.
>
> I made an estimate of the field strength of your signal by injecting a test signal at a known EMF into the loop antenna, and comparing with the level of your signal. The received FS at the strongest point (around 1330utc) worked out to be 1.8uV/m. Taking the distance between our locations as 37km, your ERP would have been 87uW. The SNR at best was around 15dB, making the noise level 0.32uV/m in the FFT noise bandwidth of 2.1mHz, or a noise density of 7uV/m per sqrt(Hz)
>
> Assuming a 50m vertical wire (heff ~ 25m),  Rrad of your antenna at 8.97kHz would be 880micro-ohms. Assuming 2.62dB directivity for an electrically short monopole compared to a dipole, and Iant of 200mA, the calculated value of ERP would then be 64uW. So there is reasonable agreement between these two calculations, the difference only being 1.3dB.
>
> Thanks for the tests,
>
> Cheers, Jim Moritz
> 73 de M0BMU

> <Dec31_08.jpg>