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The history of radar (where radar stands for radio detection and ranging) started with experiments by Heinrich Hertz in the late 19th century that showed that radio waves were reflected by metallic objects. This possibility was suggested in James Clerk Maxwell 's seminal work on electromagnetism.
A radar detector is an electronic device used by motorists to detect if their speed is being monitored by police or law enforcement using a radar gun. Most radar detectors are used so the driver can reduce the car's speed before being ticketed for speeding. In general sense, only emitting technologies, like doppler RADAR, or LIDAR can be detected.
Radar in World War II greatly influenced many important aspects of the conflict. [ 1 ] This revolutionary new technology of radio-based detection and tracking was used by both the Allies and Axis powers in World War II, which had evolved independently in a number of nations during the mid 1930s. [ 2 ] At the outbreak of war in September 1939 ...
Radar coverage along the UK coast, 1939–1940. By 1937, the first three stations were ready, and the associated system was put to the test. The results were encouraging, and the government immediately commissioned construction of 17 additional stations. This became Chain Home, the array of fixed radar towers on the east and south coasts of ...
A radar speed gun is a Doppler radar unit that may be handheld, vehicle-mounted, or static. It measures the speed of the objects at which it is pointed by detecting a change in frequency of the returned radar signal caused by the Doppler effect, whereby the frequency of the returned signal is increased in proportion to the object's speed of ...
The radar mile is the time it takes for a radar pulse to travel one nautical mile, reflect off a target, and return to the radar antenna. Since a nautical mile is defined as 1,852 m, then dividing this distance by the speed of light (299,792,458 m/s), and then multiplying the result by 2 yields a result of 12.36 μs in duration.
Christian Hülsmeyer. Christian Hülsmeyer (Huelsmeyer) (25 December 1881 – 31 January 1957) was a German inventor, physicist and entrepreneur. He is credited with the invention of radar, although his apparatus, called the "Telemobiloscope," could not directly measure distance to a target. The Telemobiloscope was, however, the first patented ...
Doppler effect. The emitted signal toward the car is reflected back with a variation of frequency that depends on the speed away/toward the radar (160 km/h). This is only a component of the real speed (170 km/h). The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the difference ...