The history of radar in the Second World War at East Prawle has been included as part of East Prawle through the Ages, but below is information for those who would like more detail.
The Principle of Radar
The principle of radar involves the transmission of radio waves over a given search area. If the waves strike an object, echoes are reflected back to the radar station, where they are amplified and displayed on a receiving screen. The time span involved between the transmission and receiving allows the range to be calculated.
The Second World War
It was a remarkable achievement that by the outbreak of WWII this highly-secret work had culminated in a chain of radar stations (known as the Home Chain) being established along the south and east coasts of Britain. This chain was later supplemented by stations able to detect low-flying aircraft, and the network was extended to other parts of the country, including the southwest of England.
The original system comprised:
Chain Home (CH): a chain of stations at “home”, as opposed to those overseas, a long-range, high-looking radar.
Chain Home Low (CHL): developed to cope with the detection of low-level aircraft.
Chain Home Extra Low (CHEL): a more powerful system for very low-level detection.
Coast Defence . Chain Home Low (CD/CHL): originally army coastal defence radars seeking out both low-flying aircraft and surface shipping; eventually absorbed into the RAF network.
CH was an early-warning and reporting system. It was outward-facing and once the invader had crossed the coast the Observer Corps took on tracking responsibilities. The radars were not particularly effective when working with night fighters, or in fighter control. Some CHL stations were later equipped to undertake limited interception control, but to rectify the principal shortcomings of the early system Ground Controlled Interception (GCI) stations were set up. Personnel at these stations were able to liaise directly with pilots and place RAF fighters in a position that allowed the aircrafts’ own (newly-developed) radars to locate an attacker both by day and by night. GCI did not replace the earlier radars, but worked with them.
All such systems operated in Devon at various locations during WWII.
Extract from Royal Air Force Air-Defence Radar Stations in Devon, the Second World War and Beyond, courtesy of the authors Mike and Andrew Passmore.