Doppler DF

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2 total messages Started by Echidna Thu, 21 Feb 2002 01:35

#167

Author: Echidna
Date: Thu, 21 Feb 2002 01:35

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I am wanting to play with some radio direction finding and am wanting to
know either some useful web sites, ideas and possibly useful books.

I had a look through a HAM radio operators book on RDF and the one that
looks most interesting to me is the Doppler DF as it gives a bearing on the
current direction you are heading.  However, when I looked the aerials that
usually go with the units they are the size that you stick on your car roof
rather than a small aerial set.  Even the ones with small stubby aerials
required a large ground plane.  Why?

Thanks,

Luke

Re: Doppler DF

#168

Author: Rod Speed
Date: Thu, 21 Feb 2002 04:51

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Echidna <echidna@hotmail.com> wrote in message
news:l9Yc8.7$dV1.23422@paloalto-snr1.gtei.net...

> I am wanting to play with some radio direction finding and am wanting to
> know either some useful web sites, ideas and possibly useful books.

You get a ton of hits using 'doppler df' in google.

> I had a look through a HAM radio operators book on RDF and the one
> that looks most interesting to me is the Doppler DF as it gives a bearing
> on the current direction you are heading.  However, when I looked the
> aerials that usually go with the units they are the size that you stick on
> your car roof rather than a small aerial set.

Thats basically due to the way doppler DF works, the antenna array
size depends on the frequency of what you are doing the DF on signal
wise, and that size is related to the wavelength of that frequency.

In other words you'll only get a small size with the higher frequencys.

> Even the ones with small stubby aerials
> required a large ground plane.  Why?

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