Second World War Radio Direction Finding Tower, Beacon Hill (EHER 82277)

The Radio Direction Finding (RDF) tower was built around 1940-1 and is an early example of a structure associated with developments in radio direction finding technology. It is a three-storey hexagonal tower built in brick with cavity walls, concrete floors and a flat roof. Each side measures 4.8 metres externally. There are two entrances on the ground floor, one of which is blocked. The first two floors have shuttered windows, the top floor has no fenestration and contains remains of an RDF array in situ.

Information from NRHE Type 287 Radio Direction Finding (RDF) Tower. A three-storey hexagonal tower built in brick with cavity walls, concrete floors and a flat roof. Each side measures 4.8m externally. There are two entrances on the ground floor, one of which is blocked. The first two floors have shuttered windows, the top floor has no fenestration and contains remains of an RDF array in situ. Surveyed at 1:500 scale as part of the Beacon Hill Fort Survey by the RCHME in February 1997. <1> This tower was built around 1940/1 and is an early example of a structure concerned with developments in radio direction finding technology. This type was able to provide gunners with a bearing of the target and a report of the fall of shot: it was used in conjunction with 6-inch coastal guns in the adjacent Beacon Hill Fort. <2> The RDF tower was not built or (apart from one brief experiment) used to guide the fire of the nearby Beacon Hill coast artillery. Together with 'sister towers' at 10 other locations (including Immingham, Tollesbury, Coalhouse Fort) it housed a naval (not army) Type 287 RDF whose specific task was to guide the remote electrical detonation of the defensive mines at the Harwich harbour entrance, in the event of an invasion or sea raid. The tower was manned by Royal Navy, not Army personnel. The coast artillery at Harwich only acquired radar in 1944 and the earliest such radar nationally was in the Dover area in late 1941-early 1942. The Type 287 towers, however, were installed prior to April 1941, at the same time as the minefields they 'observed' (to use the RN minefield jargon). Sources--Nat Archive files on Observation minefield and naval radar, Army Eastern Command lists of 'vulnerable points'; (1941-43), files on manning and paying off of observation minefields & their radar. The tower did do one recorded trial cooperating with the local coast guns in Oct 1941, but that was not its essential work. It was shut down in 1943 while the nearby coast artillery remained in operation. <3> Additional references <4> <5> <6>