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Pioneers & Progress. Like most great inventions, radar had many inventors.
Among those in the U.S. who had a hand in its development were: a Navy quartet. of physicists and radio hams—Albert H. Taylor, Leo C. Young, Robert M. Page and Louis A. Gebhard—who pioneered radar in the '205 and '303; the Signal Corps' Colonel Roger Colton (now an A.A.F. major general), whose laboratory staff at Fort Monmouth designed the first Army set; Stanford University's R. H. and S. F. Varian, who invented the important klystron tube; and a great anonymous army of scientists at M.I.T.'s Radiation Laboratory, Bell Telephone Laboratories, General Electric, many another industrial laboratory. The U.S. also owes much to Rear Admiral Harold G. Bowen, who, as chief of the Naval Research Laboratory, sparked its radar pioneering.
U.S. progress in radar was paralleled by a team of British physicists under Sir Robert A. Watson-Watt. (The British first called it "radiolocation," later accepted the U.S. word "radar."*) There were also the Germans, who were known to be experimenting with radar as early as 1935; the Japs, whose physicist Hide-tsugu Yagi was working on basic shortwave studies long before the war (the U.S. Navy called its early radar antennae "yagis"); the French, who in 1936 installed on the Normandie a crude radar for detecting icebergs.
The one man with the best claim to discovery of radar's principle was the 19th Century German physicist Heinrich Hertz, who in 1887 bounced a hertzian (radio) wave off a zinc plate and caught its echo on a resonant circle of copper wire.
Idea into Miracle. Radar's significant history began one hot summer's day in 1922, when the Navy's Albert Taylor and Leo Young, noticing that ships passing up & down the Potomac distorted short-wave signals they were sending across the river, conceived the idea that radio waves might be useful in detecting enemy warships. By 1940, Army & Navy radio experts had built a few bulky sets which could locate sizable objects on the water or in the air, but could not identify them.
The real miracle of radar was what happened in the next five years: a job of U.S. and British scientific teamwork which created almost overnight a revolutionary instrument, and a vast industry which would normally have taken a generation to develop.
Shouts & Echoes. The basic secret of radar is that short radio waves behave very much like light. In the spectrum of electromagnetic radiation, which ranges from the extremely short cosmic rays (trillionths of an inch) and gamma rays (which are released in an atomic bomb) to extremely long electric power waves (6,000 miles), radio and light waves are almost next-door neighbors, though light waves are much shorter than radio.
Like light, the ultrashort radio waves used in radar can be focused in a beam, are reflected by solid or liquid surfaces, travel with the same speed as light (186,000 miles a second). But for "seeing" distant objects, radio waves have a great advantage over light: they penetrate fog, clouds and smoke, reach out to far greater distances than the naked eye. And unlike light, radio impulses can easily be controlled to give an exact, automatic measurement of the distance to the detected object.