By: Suad Čobo
Traditional running may be healthy, but sometimes boring. ARDF Championships, in my opinion, have more to offer: you can learn to use a map (which usually doesn't have a defined route of the race), make new friends and learn something new about radio and physics! Even non-licensed radio amateurs with minimal knowledge of radio waves and Morse code can compete, and maybe even win a prize.
ARDF Competitors after the Closing Ceremony of ARG-ARDF Zavidovići Open 2019 (Photo: Saša Lisul E74SL / Radio Klub Pousorje E75RKP) 
Amateur Radio Direction Finding (ARDF) is an amateur racing sport that combines radio direction finding with the map and compass skills of orienteering. It is a timed race in which individual competitors use a topographic map, a magnetic compass and radio direction finding apparatus (ie. a radio receiver with a directional antenna) to navigate through diverse wooden terrain while searching for radio transmitters (or foxes in amateur radio jargon). The rules of the sport and international competitions are set by the International Amateur Radio Union (IARU). The sport has been most popular in Eastern Europe, Russia, and China, where it was often used in the physical education programs in schools. 
How does the contest work?
A portion of an orienting map of an ARDF compeition (Photo: Wikimedia Commons) 
ARDF events use amateur radio bands of either 2 or 80 m of wavelength, since they are almost universally available worldwide without special licensing from government agencies. On most events, there are 5 transmitters on the unknown track and a beacon at the end, and each category (based on sex and the age of contestants) has their own set of transmitters they need to find in order to get points. Points are given based on the running time and the number of mandatory transmitters, and the results are divided into every category used during the event, and sometimes there is also a separate list of radio clubs, where they are given points based on the number of places occupied by every category.
A transmitter, orienting control flag, a paper punch, and electronic punch at an ARDF control (Photo: Wikimedia Commons) 
Before the contest, contestants have to put their receiving equipment to a place decided by the event organizer to prevent scanning the nearby transmitters before their start time, which is selected randomly and not the same for all contestants. Depending on the budget of the event, as a registration device, SportIdent, a paper punch, or just a regular ink stamp may be used. During the race, use of cellular phones or a radio station not designed for receiving the band used for the event is prohibited.
Variations of ARDF Contests
Fox Oring is a variation of the sport that requires more orienteering skills. In a Fox Oring course, the radio transmitters put out very little power, and can be received over only very short distances, often no more than 100 meters. The location of each transmitter will be indicated on the map with a circle, which indicates the area in which it's transmissions can be heard. A competitor must use orienteering skills to navigate to the area of the circle on the map and only then use radio direction finding skills to locate the very low power transmitter.
Another variation of the sport, Radio Orienteering in a Compact Area, requires less athletic skill and more technical radio direction finding skills. In a ROCA course, the transmitters put out very little power, typically 10 to 200 mW, and can be received over only very short distances. Because of the low power and short distances involved, most ROCA competitors walk the entire course, and focus their attention on the radio direction finding tasks rather than navigation.
 Pousorje, S. L. (2019, 8 25). Retrieved from Facebook page “Radio klub Pousorje”: https://bit.ly/30T4xIQ
 Amateur radio direction finding. (n.d.). Retrieved from Wikipedia (English): https://en.wikipedia.org/wiki/Amateur_radio_direction_finding
 User:Kharker, W. (2006, 3 12). File:Ardf_map.png. Retrieved from Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Ardf_map.png
 Hunt, D. (2006, 3 12). File:Ardf transmitter-2m.jpg. Retrieved from Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Ardf_transmitter-2m.jpg