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RDF Tower DoB ID: e29831

Located at a remote site about 2 miles northeast of the airfield, this octagonal blast wall on Ibsley Common surrounds a similarly shaped concrete foundation inside. They are the tangible remains of a once top secret wartime direction finding station commonly referred to as HF/DF or "Huff Duff". The equipment and its operators were accommodated within the confines of an octagonal 3 storey wooden tower bolted to a concrete plinth. The tower was 30 feet high and was constructed of wood to minimise both electrical and magnetic interference. It was topped by a fixed small aerial array of four vertical dipoles arranged in a square configuration. There is another building 100 yards to the SE that may have housed a generator, or was simply crew accommodation, or both. Adjacent to this building is an air raid shelter.

The key feature and main advantage of Huff Duff was its use of a cathode ray tube display and fixed aerial that would instantaneously reveal the direction of the transmission without the need to rotate the aerial. These small radio direction finding stations were the last link in the RAF fighter control system. Two or more stations 30 miles apart could by a system of triangulation, determine the direction and position of a squadron's lead aircraft from its r/t transmission, information that was then passed to the sector control. Once the coordinates were known, the squadron could then be guided to intercept the enemy aircraft that had been located by radar and observer posts. Each station was also equipped with a "Homer", a radio transmitter beacon to help Allied aircraft navigate their way home in bad weather.

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SU1710 : Discovering RAF Ibsley: HF/DF station (2)