Radio as an entertainment medium may have been supplanted by Pandora, SiriusXM, Spotify and YouTube, but radio wave detection is an integral part of our lives, from our morning weather report to air-traffic control towers, from cellular telephony to remote-controlled toys.
On 26 February 1936, Scottish physicist Robert Alexander Watson-Watt convinced the British Air Ministry that “that radio waves could be used to detect more than storms.”
In the late 1880s, the German physicist Heinrich Rudolph Hertz was first to discover an invisible form of electromagnetic radiation, radio waves, which James Clerk Maxwell had predicted.
Hertz created visible radio waves and then calculated their speed, the same as the speed of light. His peers “attach[ed] his name to the unit of frequency; a cycle per second is one hertz.”
Watson-Watt designed the first Radar (for RAdio Detection And Ranging) set with the goal “to help airmen locate and avoid approaching thunderstorms.”
He also discovered “that radio waves could be used to detect more than storms.” It was this application that he demonstrated to the British Air Ministry in 1936.
A Royal Air Force Heyforth bomber was used for the War Ministry demonstration at Daventry. Three times the plane passed overhead and three times the main beam of a BBC short-wave radio transmitter picked up reflected signals.
Impressed, the air ministers embraced the new technology and by September 1939, when war broke out in Europe, the British had a network of radar installations covering the English Channel and North Sea coasts.
By 1940, Germany had its own radar and search light system, the Kammhuber Line.
Of course, the military continues to use radar and attack radar installations.
After World War II, many industries adopted radar. Navigators use radar to direct ships and airplanes; law enforcement, to detect a speeding cars and trucks; and meteorologists, to detect atmospheric phenomena that inform weather (and storm) forecasts.
Weather radar images map reflected atmospheric particles.
Built in 1961, the Stanford Dish (featured image) was designed to operate in the event of a nuclear war and to “learn the characteristics of large radars operating within the Soviet Union.”
