From: John Woodgate
Subject: Re: Radio Direction Finding
Date: Tue, 5 Nov 2002 17:56:28 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Tue, 5 Nov 2002 20:08:02 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Keith Wootten
wrote (in ) about
'Radio Direction Finding', on Tue, 5 Nov 2002:
>In message , Leon Heller
>>A shielded loop antenna (you can make one from co-ax cable) only picks up
>>the H field. I think the ARRL Antenna Handbook has some info on them. They
>>are directional, like all loop antennas.
>The problem with a loop on its own is the figure 8 response. My
>application can't tolerate the ambiguity and I really need cardioid (or
>better), but without using an omnidirectional voltage probe component.
>It needs to work at 40MHz.
I don't think there is a small-volume solution that does not need an
electric antenna. How much room do you have and what is the minimum
field strength? A 10 cm monopole or spiral with active matching might
give you enough signal-to-noise to allow you to resolve the ambiguity,
even if you can't get a null.
I don't have any details of active matching of short antennas, but I'm
sure there is stuff on the web.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
PLEASE do NOT copy news posts to me by E-MAIL!