Re: LF: Loop TX antennas at VLF?

[Andy Talbot <andy.g4jnt@gmail.com>]

Here's an Excel S/S I did in the 73kHz days.   Other people have updated versions now, but it serves to get you into a region to design from - or know when to not bother

 

http://www.g4jnt.com/DownLoad/MAGLOOP.XLS

Andy

www.g4jnt.com

 

On 18 March 2011 14:09, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:

Just wondering if anyone has done the maths to work out what sort of ERP could be expected at 8.97kHz with, say, 100W to a smallish loop antenna in the garden?

It would certainly avoid the need for very very large matching coils and may be easier to engineer than a Marconi. Even an efficiency of -80dB would allow 1uW ERP and, judging by results from G3XIZ with around 2uW, this could be useful with long stable carrier transmissions of several hours. Most of us could run a loop with an area of 100sq m. with thickish wire in our gardens. A loop might also be more practical for portable operations perhaps with a triangle with one high support.

Certainly my own results with WSPR at 136 and 500kHz with just a few watts and quite thin wire and around 80sq m loop area were encouraging. Mind you, 9kHz is very much lower than 136kHz, so the radiation resistance would be tiny I assume.

73s
Roger G3XBM

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