Direction Finding (D.F.)

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Radio Direction Finding is one of the many diverse aspects of Amateur Radio. It involves the tracking down and locating a hidden radio transmitter using a special directional receiver. All competitors in the event start at the same place at the same time. When the transmitter is heard, a compass bearing is taken on the direction of the signal and plotted on a map. The competitors then drive off to another suitable location, take another bearing, and where the two bearings cross on the map is where the transmitter should be located. The winner is the competitor who finds the transmitter operator first.

A theoretically near-perfect set of bearings on a map. In practice the angle of intersection of the bearings will be anything but 90 degrees, meaning that a certain amount of error will come into where the bearings cross. In addition a small error could come into the actual bearing, through the signal being deflected by buildings, metal pipes in the ground etc. At best where the bearings cross should be considered a search area and extra bearings taken to narrow down the location of the transmitter.

Events take place at two levels. Local events run by a local Radio Society are held, usually on a Friday evening from about 7.30 p.m. until 9.00 p.m. There is usually only one transmitter to find, and after the event everyone meets up at a pub to swap stories and to see the results. National events are held throughout the summer all over the country. Radio Clubs take it in turn to host events, which can be as far apart as Torbay in Devon, to Ripon in Yorkshire, so a fair amount of travelling (and dedication!) is required. On these events there are two transmitters to find, and the winner is the competitor who finds his second transmitter first. There are eight National Qualifying events throughout the year, and on each event, two teams qualify for the National Final, which is held in September, at which event there are three stations to find. At each National Qualifying event points are awarded on a grand-prix basis and are accumulated throughout the season, for a trophy to be awarded to the competitor with the highest number of points at the end of the year. Special events are held at either end of the season to add further interest. These are organised locally, but invites are always issued to other clubs nationally. The "Snowman" is usually the first event of the year at the end of January, with the "Mid-Essex Trophy", and "Mid-Thames Treble Night", in the autumn, after the National Final. DATES FOR 2009

Occasionally the hunter becomes the hunted, as competitors take it in turns to be the hidden station. This gives them the chance to get their own back on other competitors, as the one hiding can be as cunning as he likes in finding a suitable place to hide, provided the site is not dangerous, and bearing in mind that ultimately the contest must be "do-able". See the report of the 2005 "Snowman" DF and the End of Season DF 2008 for the hidden station's perspective. The "Snowman" took place in early February 2009. Click here for the report and lots of photos.

Links to other sites:

Click here for a report on the NATIONAL FINAL in September 2000 Click here for a report on the NATIONAL FINAL in September 2003 Click here for a report on the NATIONAL FINAL in September 2005 Click here for a report on the NATIONAL FINAL in September 2006 Trophies Winning the Rosebowl

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