Topband: Loops, Directivity and DX

[Roger Parsons]

In the UK 160m DF competitions are quite popular - a
station is hidden in some horrible and inaccessible
place usually within about 20 miles from a fixed
starting position. The hunters use either loops or
ferrite antennas, often with a sense circuit as well.
To make it more fun some of these competitions take
(took) place at night. The ONLY way to get a remotely
accurate bearing is to null the received signal. 

My experience was that on a true ground wave one can
obtain 2-3 degrees accuracy quite easily. On sky wave
- which at night can be a station within a mile or two
- the accuracy was terrible. Major bearing shifts (>30
degrees), or the inability to get a null at all, were
quite common. I think that a certain Mr Adcock showed
how it could be done properly 70 or 80 years ago, but
his array is a little impractical for portable use.

I completely fail to see how one could use a loop to
determine the direction of a weak DX signal, as the
main lobe is very broad, and the signal is almost
bound to be inaudible in the null.

On a separate topic DU9/N0NM peaked about 579 here
before my sunrise. Despite calling myself silly I
don't think I got even a QRZ. There's always tomorrow!

73 Roger
VE3ZI



	
	
		
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