Radio Direction finding is a great part of the Ham Radio Hobby.
(I did it Air-Mobile in Viet Nam too, with the ASA.)
The transmitter can be TINY.
I use a PIC to control a hand-held 2 meter rig. in an Ammo box.
(Caution! Licensing Issues!)
But you could build a very small oscillator coupled to an antenna.
The receiver should be capable of  displaying signal strength, and 
better yet, have an attenuator.
The receiver should be shielded, so it only gets signals from the antenna.
(Hams often use the body for this purpose, which goes a long way to 
explain their girth! :) )
The direction is often a matter of the receiver's antenna design.
I've used a Yagi, double ducky, and a quad duckie system so far.
Multilateration is the best technique.
Reflections are a bear!


Luis Moreira wrote:

>Hi Guys,
>A few years back I found a few web sites about this competitions in the
>US where you go and track a radio signal, like "radio hunting", I can
>not remember the proper name for it.
>I am interested in info about the transmitter and receiver for these
>systems. 
>I am looking for some kind of system where I would have a beacon and a
>detector that would be able to detect strength of signal. I do not need
>that much range, 5 meters would be plenty although more would be ok. The
>aim is to get a small detector that will give an analogue output
>proportional to the strength of the signal being transmitted but also be
>directional i.e. if moved around will detect where the stronger signal
>is coming from.
>The TX also needs to be small.
>Thanks,
>Best regards
>		Luis
>
>
>
>
>  
>

-- 
  *
  |  __O    Thomas C. Sefranek   WA1RHP@ARRL.net
  |_-\<,_   Amateur Radio Operator: WA1RHP  
  (*)/ (*)  Bicycle mobile on 145.41, 448.625 MHz

http://hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org


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