[Lowfer] K9AY vs. multi turn loop

[Bill Ashlock]

Dale,

I finally got the chance to look into how these K9AYs work. In the simplest, 
one loop design, you actually have a loop that is sensitive to both the 
H-field and E-field. The amount of series resistance (0 to 1 kohm) 
determines how much E-field sensitivity there is. This gives rise to the 
cardioid pattern and I've seen similar designs, using much smaller loops and 
a small E-probe signal summed in via a variable resistor, for direction 
finding.

Some day I'll transmit on both a loop and a vertical in the right portions 
to form a cardioid pattern rather than a figure '8'.

Bill A


>From: Dale Parfitt <parinc@gte.net>
>Reply-To: lowfer@mailman.qth.net
>To: lowfer@mailman.qth.net
>Subject: Re: [Lowfer] K9AY vs. multi turn loop
>Date: Mon, 20 Oct 2003 08:59:31 -0400
>
>
>
>Johan Bodin wrote:
>
> > Dale,
> >
> > > On the K9AY I would erect 2 loops and be able to switch the null 
>N-E-S-W.
> >
> > You can get 8 null directions from just two loops simply by adding two
> > DPDT relays to the "outdoor box". If you connect the two loops in 
>series,
> > the result will be a funny looking two-turn loop with an average winding
> > plane that is at +45 degrees to the physical loops. Then reverse the
> > polarity of one of the loops and youl'll get -45 degrees. Together with
> > the original configuration, this brings you nulls in 
>N-NE-E-SE-S-SW-W-NW.
> >
> > My antenna works great on LF but sometimes behaves a little bit
> > strange in the upper half of the MW band. Probably because the loop
> > wire length becomes a considerable fraction of a wavelength. Could
> > have something to do with angle of arrival too, I guess...
> >
> > Oh, I almost forgot, the termination has to be adjusted slightly when
> > switching between "normal" and "45 deg" null directions.
> >
> > 73
> > Johan Bodin SM6LKM

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