Re: LF: VLF - G3XIZ

[Roger Lapthorn <rogerlapthorn@gmail.com>]

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" <james.moritz@btopenworld.com> 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>