Cold War microwave tower at Sibleys (EHER 46722)

Post-War (1960s) Microwave Relay Station, steel lattice structure, in use and in good condition.

Conventional bombing during the Second World War revealed the disruption that could be caused to telecommunications when underground cables were severed. In the early 1950s, in an attempt to counter this threat, exchanges were excavated deep beneath a number of cities. But even these were vulnerable to awesome power of the H-bomb and by the mid 1950s development of an emergency microwave communications system had begun, generally (but perhaps not officially) known as ‘Backbone’. The system was designed to maintain government communications across the country between emergency centres of government and between military establishments. Other dedicated microwave communications systems were also developed by the military from this date. Many also carried civil communications networks, including early television transmitters. Microwave communications towers are found distributed across the whole country but tend to be sited in prominent positions away from urban centres. Considerable typological variation is found in their design, which is in part chronological. Towers erected in the mid 1950s are formed from steel sections and may be stepped to accept contemporary horn shaped aerials. In the 1960s hollow cylindrical towers were adopted with platforms on which to mount aerials. Later in the decade modular steel-framed towers were developed, whose flexibility allowed them to be easily extended. Other variations are also found. The 'Sibleys' late 1960s microwave communications towers are constructed in rectangular modules to allow for easy upward and sideways extensions. New circular shaped dishes were one factor in the adoption of this design. Site Assessment = Consider for Listing. <1> NRHE data transfer: Post-war Microwave Relay Station. The tower was probably erected during the early 1960s as part of an emergency communications network generally known as 'Backbone'. The tower is formed of prefabricated modular sections, comprising columns, rectangular hollow sections, horizontal bracing, and solid rod diagonal and plan bracing. The structure is fitted out with standard access ladders, platforms and aerial mountings. The advantage of this type of tower is that it gives a larger surface area on which to mount dish aerials and may be easily extended upwards or laterally. <2> <3> See also: <4>