In the early days of World War II, British scientists had just completed whatwould be the most advanced defense system of their day: a network of radio-signal stations that could detect the approach of Nazi bombers, day or night,in fair or foul weather. This network was given the ungainly title "Radio Detection and Ranging" but is most commonly known as radar. Though the list of scientists who contributed to its creation is long, the name at the top wouldcertainly be Sir Robert Watson-Watt, whose work made the creation of radar possible. Watson-Watt was born on April 13, 1892, and as a student in Brechin,Scotland, he developed an interest in radio telegraphy; in 1915 he began working for the London Meteorological Office using radio waves to monitor thunderstorm activity, an essential task to aid the safe flight of early fragile aircraft. He continued to work for the government for much of his life, first bysupervising two radio research stations and later by researching the use ofradar for navigation. All this time, Watson-Watt knew that radar could eventually be used for echolocation--in fact, he patented this concept in 1919, anticipating the future construction of a radar location device.
In the early 1930s, Watson-Watt was appointed scientific adviser to the Air Ministry and was given the task of designing just such a device. Several important discoveries were instrumental to the invention of the radar system; forexample, in 1922 the cathode-ray tube, which would be used for visualizing the returning radar signal, became available. In 1936 pulsed radar replaced continuous-wave emitters; the old system could detect only the presence of an object, while the pulsed signal could also pinpoint its location. Finally, in 1939 the practical microwave transmitter was constructed, allowing the radar locater to operate through cloud and fog. The construction of a radar defenseshield, which was completed in secrecy, passed its first test during the Battle of Britain, where the early warning system made possible the Allied victory over the Nazi air force. Ironically, German scientists had reportedly alsobeen working on a radar location system. However, Adolf Hitler (1889-1945) and Hermann Göring (1893-1946) saw it as useful in a defensive situation only; since Germany would never be on the defensive end of an air war, they concluded, the development of radar was of low priority. Watson-Watt was invited to the United States in 1941 to help Americans develop their own radar system. Since World War II, the use of radar for nonmilitary application has become widespread. Watson-Watt was knighted in 1942. He died on December 5, 1973.