What is Radar?

Radar is an acronym for radio detection and ranging. It is a system used to detect, range (determine the distance), and map objects such as aircraft and rain. Strong radio waves are transmitted, and a receiver listens for any echoes. By analyzing the reflected signal, the reflector can be located, and sometimes identified. Although the amount of signal returned is tiny, radio signals can easily be detected and amplified. Radar radio waves can be easily generated at any desired strength, detected at even tiny powers, and then amplified many times. Thus radar is suited to detecting objects at very large ranges where other reflections, like sound or visible light, would be too weak to detect.

 Different Forms of Radar

"Three soldiers of the United States Army sit in place at a radar used by the 90th Coast Artillery in Casablanca, French Morocco"
Image courtesy of National Archives and Records Administration

"A Radar room aboard the USS Hazard"
Photo by Duane Gallager, 1985