People have been doing radio direction finding as a sport for decades. I learned a lot from weekend transmitter hunts - we'd have one team hide somewhere in the general vicinity of the city (had to be heard from the starting point), transmit a signal on the 2 meter band, and the rest of the teams would hunt them down.
Sometimes it would be a tiny unattended transmitter. One of our favorite tricks was to bury the whole thing and use a 1/4 wave brass rod as an antenna, and insert it into a dry weed in a vac
Its official name is "Radio Direction Finding", but goes by several nicknames like "foxhunting", "transmitter hunting", or "t-hunting".
The "home base" of RDF information is the "Homing In" website at http://members.aol.com/homingin/
The author of that site has written a very good book explaining various techniques and containing plans for building various kinds of directional antennas.
Most T-Hunters are amateur radio operators (http://www.arrl.org), but that's not a requirement, since you aren't transmitt
Our local radio club did a foxhunt sometime last year.
Antennas ranged from simple yagis, phased paper clips on a yardstick connected with coax, a mailing tube and aluminum foil, one guy even had his hand held radio inside a metal trash can. Most were homebrew, but some were commercially built.
It's pretty easy to do, actually. Some people used bi-directional antennas, rotated them until they could no longer hear the signal, and then went off to either of the null directions. Others used highly-directional antennas to point them in the right direction. Aiming it towards the transmitter might get you close to the right direction, but having a null in the back somewhere really helps to pinpoint things. You just keep doing this until you find the signal source.
You just have to worry about the terrain affecting the transmitted signal (your antenna might lead you to where the transmitted signal is reflecting off something). Oh, and you'll get lots of strange looks from people.
That's nothing... (Score:5, Interesting)
Sometimes it would be a tiny unattended transmitter. One of our favorite tricks was to bury the whole thing and use a 1/4 wave brass rod as an antenna, and insert it into a dry weed in a vac
Re:That's nothing... (Score:0)
Re:That's nothing... (Score:5, Interesting)
The "home base" of RDF information is the "Homing In" website at http://members.aol.com/homingin/
The author of that site has written a very good book explaining various techniques and containing plans for building various kinds of directional antennas.
Most T-Hunters are amateur radio operators (http://www.arrl.org), but that's not a requirement, since you aren't transmitt
Re:That's nothing... (Score:1)
Antennas ranged from simple yagis, phased paper clips on a yardstick connected with coax, a mailing tube and aluminum foil, one guy even had his hand held radio inside a metal trash can. Most were homebrew, but some were commercially built.
It's pretty easy to do, actually. Some people used bi-directional antennas, rotated them until they could no longer hear the signal, and then went off to either of the null directions. Others used highly-directional antennas to point them in the right direction. Aiming it towards the transmitter might get you close to the right direction, but having a null in the back somewhere really helps to pinpoint things. You just keep doing this until you find the signal source.
You just have to worry about the terrain affecting the transmitted signal (your antenna might lead you to where the transmitted signal is reflecting off something). Oh, and you'll get lots of strange looks from people.
As the parent said, check the http://arrl.org/ [arrl.org].
Re:That's nothing... (Score:1)