[Lf] Re: AMRAD Antenna ?]

[Andre' Kesteloot]

John Rabson wrote:

> We use this technique of grounding  both ends of a wire in Cave Radio work
> as it enables us to communicate to a greater depth than does the
> conventional method, which uses resonant loops a metre or two in diameter.
> It has also been used  on 73 kHz at a location in  Oxfordshire - the station
> was heard at a distance of 250 kilometres. This technique has been referred
> to as an earth bipole.
>
> I understand from Graham Naylor that during the recent cave rescue operation
> in south-western France, where this technique was used, the rescue party
> developed a new variation at the surface station. Instead of feeding the
> wire in a symmetrical manner at its centre, the two halves of the bipole
> were strapped together and fed against an earth connection near the
> mid-point of the wire. This seemed to produce equally good results as far as
> underground communication was concerned and produced a useful reduction in
> the level of interference from LORAN.
>
> This technique has been dubbed the earth tripole.
>
> 73 de
>
> John Rabson G3PAI