The Flying Beams
". . . the first World War was fought by chemists, the Second by physicists." Brian Johnson, The Secret War, p. 61
By the 1930s, electronics were starting to play an increasingly important role in aerial warfare. In this arena, however, the Germans and the British had progressed along two entirely different courses of development. The British, who were preparing primarily for a defensive stance, had placed their major emphasis on the development of radar for the detection of incoming aircraft. By 1940, they had two types of radar stations in operation: the CH, orchain home, for detecting high-flying aircraft; and the CHL, or chain home low, for detecting aircraft flying at low altitudes. (See Chapter 7.)
Unlike the British, the Germans preferred to rely on electronic navigational aids. Before World War II started, they established a series of medium frequency beacons that transmitted a call sign followed by a 20-second continuous note on the 176-580kc/c band. 1 Aircraft could home in on these signals, and by taking bearings from these transmissions they could establish their precise location. By March of 1940, the Germans had forty-six of these beacons in operation in Germany. After their advances in the west, they installed an additional thirty-eight beacons and eleven broadcasting stations outside of Germany. These were all in operation by September of 1940. The British, however, quickly developed electronic countermeasures for use against these beacons. They transmitted masking beacons, called meacons, to confuse the Luftwaffe flight crews by giving them false bearings.
While the British were perfecting their radar and their defensive measures, the Germans were preparing their offensive electronic equipment and techniques.