Amateur radio direction finding (ARDF) is also referred to as ‘radio orienteering’ and is another form of radio sport.
Sometimes, we might feel as though life is a little dull – that there is no adventure left. But in truth, there are countless incredible experiences to be had, many of which can be enjoyed from the comfort of your home.
With a police scanner for instance, it is possible to pick up a huge and fascinating range of radio chatter – letting you in on an entire underground movement and culture of secret communications. You can use a basic shortwave radio meanwhile to communicate in code, or to bounce messages off the moon.
And by engaging in ARDF, you can turn this into an adventure where you get outside and set off in search of all the source of a signal.
How it Works
ARDF is a timed race that challenges participants to utilize a topographic map, magnetic compass, and radio direction finding apparatus in order to move through thick woods in search of radio transmitters.
In other words, a radio will be situated in order to broadcast a signal, and using their equipment, they will attempt to track down the location of that signal by understanding how it propagates and by moving in the direction where the signal gets stronger.
ARDF events will tend to use radio frequencies on a two meter or eight meter amateur radio band. These bands are chosen because they are available in all countries to all amateur radio licensees.
ARDF transmitters are designed with intentionally low power output and will transmit in Morse code. The transmitters will send a unique identification that is easy to interpret, even if you are unfamiliar with Morse code – you simply need to count the number of dots following the dashes. All of the transmitters on the course will emit the same frequency.
The only requirement for the receiver equipment used by the competitors then, is that it should be capable of receiving the signal being transmitted. In theory this could work with any handheld two-way radio capable of listening to those frequencies.
Directional antennas however are recommended, seeing as they are more sensitive to radio signals arriving from certain directions. That in turn will allow you to quickly identify which direction the signal is coming from.
Normally, the antenna used on the two meter band will be two or three element Yagi antennas, made from a flexible steel tape. On the 80 meter band, they will use either a small loop antenna, or an antenna wound around a ferrite rod. These have a bidirectional receiving pattern. ARDF equipment of course should be designed to be lightweight and easy to carry.
The regulating body – the IARU – specifies that clothing is up to the competitor to choose, though most will choose comfortable outdoor clothing.
These events challenge a range of skills, from technical radio operation skills, to the ability to read maps and move quickly across unpredictable terrain.