Radio Direction Finding (RDF) and Transmitter Hunting
Find resources for building and using equipment for radio direction finding, including antennas, receivers, and fox hunting techniques.
Radio Direction Finding (RDF), often called "foxhunting" or "T-hunting," challenges operators to locate hidden radio transmitters using specialized antennas and receivers. This activity is popular worldwide, from casual local events to competitive Amateur Radio Direction Finding (ARDF) contests. Hams use RDF skills for sport, but also for practical purposes like tracking down sources of interference or locating lost equipment. It's a hands-on operating mode that combines technical skill with outdoor activity, often involving teams and mobile stations.
Many hams enjoy building their own RDF equipment, and this category features numerous projects for antennas, attenuators, and receivers. Operators can find designs for specialized antennas like the Adcock array for HF or compact yagis for VHF, along with complete plans for fox transmitters and controllers. There are also resources covering Doppler direction finding systems, which are popular for mobile T-hunting, and information on how to set up and participate in ARDF events, including details on scoring and rules.
Subcategories
- Clubs (8)
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A home made yagi antenna featuring 6db forward gain and 22 Db front back -
The 80 metre fox-or/test transmitter is a small low power transmitter which is designed to be used as an alignment aid for running up 80 metre foxhunt or ARDF receivers. It is also usable as a micro transmitter for fox-or-ing events. -
A full superhetrodyne SSB fox hunting receiver kit -
This low power transmitter is developed for ARDF exercising purposes but of course can be used as super QRP transmitter either. With 1 or 2 meter wire as antenna and a ARDF receiver with ferrite-rod antenna the range is about 100m but with better antennas and a 'real' receiver the range is probably much larger. -
Using APRS For Direction Finding -
Ardf holland, information about ardf activities in the netherlands, in english and dutch -
Far Circuits offers a catalog of printed circuit boards (PCBs) for various radio direction finding (RDF) and transmitter hunting (T-hunting) projects. -
Here is a high-performance hand-held beam antenna that is easy to build and guaranteed to improve your downlink from the LEO satellites over ANY rubber duck or mobile whip -
Lots of information of hidding transmitters, building portable yagi antennas, s-meters, and much more -
All about radio direction finding (RDF) -
80-meter peilontvanger / receiver includes printed circuit sample and list of components -
Lots of projects and introductions to RDF and T Hunting -
An introduction to RDF contesting in southern California, updated from a paper originally submitted for Proceedings of the 1992 West Coast VHF/UHF Conference. -
N6QAB Radio Direction Finding Web Site, DF vehicles, transmitters, sniffers, dopplers, TH-D7A -
The Adcock antenna has been used for a long time for RDF. It is basically an interferometer. -
This processor controlled autoranging sniffer has become popular for vehicle based foxhunting in Australia -
Amateur radio direction finding, transmitter hunting web site from San Francisco. Triangulating a radio signal direction and plotting its bearing on a map. Hunters use doppler systems for tracking hidden transmitters anywhere in the san francisco bay area, fremont california -
VectorFox is a software born to incorporate a PC into the fox hunting environment. VectorFox is able to take inputs from up to 5 sources, such as a 2m beam, a 2m signal meter, a TDOA, etc, and display the results on the screen. VectorFox also accepts Agrelo inputs. From these results the operator can choose which indication is best and have a line drawn on the map in the direction of the signal. -
Fox hunting site with details of a PC based DF system -
Fox Hunting for Scouts. Jamboree can be an opportunity to promote ARDF among Scouts all around the world. -
A collection of pictures for a mobile antenna setup for T-hunting. -
About Amateur Radio Direction Finding events, sprint and Fox-Oring spcialities. Sprints are intended to bring ARDF nearer to the public and to attract potential sponsors and new athletes to ARDF. Foxoring encourages ARDF enthusiasts to improve their orienteering skills. -
RDF Equipment Ideas for VHF Foxhunting and Radio-Orienteering. This information is primarily for the Amateur Radio two-meter band -
When it is time for you to hide a Hidden Transmitter there are several ways to control the transmission timing and audio of the transmitter.The most basic of these is of course the manual method of hiding in the bushes with your trusty HT and talking on and off for several hours. -
Samples and documentation on RDF setups -
The Utah Amateur Radio Club - Radio Direction-Finding RDF -
If your club holds only two-meter ARDF events, you are missing half the fun. There is another international foxhunting band, too.