Who invented radar?
Quick answer
Radar had many inventors. Heinrich Hertz showed in the 1880s that radio waves bounce off objects; Christian Hülsmeyer patented a ship-detection device in 1904; and Scottish physicist Robert Watson-Watt, with Arnold Wilkins, demonstrated a practical aircraft-detection system in 1935, which became Britain’s wartime radar network.
RADAR stands for RAdio Detection And Ranging, a name coined by the US Navy in 1940. Several countries, including the UK, US, Germany, France, the Soviet Union and Japan, developed radar independently and in secret in the 1930s.
The key steps
- 1886–1888German physicist Heinrich Hertz proves radio waves exist and reflect off metal objects
- 1904German inventor Christian Hülsmeyer patents the “telemobiloscope” to detect ships in fog
- 1922US Navy researchers notice ships interfering with radio signals
- February 1935Robert Watson-Watt and Arnold Wilkins detect a bomber with radio waves at Daventry, England
- 1937–1939Britain builds the Chain Home radar network along its coast
- 1940The cavity magnetron, developed in Birmingham, makes powerful, compact radar possible
How radar works
- A transmitter sends out a pulse of radio waves.
- The waves hit an object, such as a plane or a raincloud, and bounce back.
- A receiver picks up the echo.
- The time delay shows how far away the object is, and the direction of the antenna shows where it is. Changes in the echo’s frequency (the Doppler effect) reveal how fast it’s moving.
Why it mattered in World War II
Chain Home radar gave Britain early warning of incoming German aircraft during the Battle of Britain in 1940, helping a smaller air force defend the country. Radar also helped ships and aircraft find enemies at night and in bad weather.
Radar today
| Use | Example |
|---|---|
| Air traffic control | Tracking planes around airports |
| Weather forecasting | Doppler radar shows rain and storms |
| Cars | Adaptive cruise control and collision warnings |
| Police | Speed guns |
| Space | Mapping planets and tracking satellites |
Another invention with a tangled history: who invented the light bulb.
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