Radar

Radar is a system that uses <a href="/facts/Radio_wave/LzrVhgbn">radio waves</a> to determine the distance (<a href="/facts/Ranging/rGJdrNrl">ranging</a>), <a href="/facts/Direction_(geometry)/Tj24mTJ8">direction</a> (<a href="/facts/Azimuth/kEyt9nJ3">azimuth</a> and <a href="/facts/Elevation_angle/5cVnNof3">elevation angles</a>), and <a href="/facts/Radial_velocity/B3NmbVLP">radial velocity</a> of objects relative to the site. It is a <a href="/facts/Radiodetermination/NoJAatml">radiodetermination</a> method used to detect and track <a href="/facts/Aircraft/EhC4mBep">aircraft</a>, <a href="/facts/Marine_radar/G5h3tyk0">ships</a>, <a href="/facts/Spacecraft/YQqQaUw0">spacecraft</a>, <a href="/facts/Guided_missiles/C5VwQClz">guided missiles</a>, <a href="/facts/Motor_vehicle/AaXamA0w">motor vehicles</a>, map <a href="/facts/Weather_radar/S7BlhMzF">weather formations</a>, and <a href="/facts/Terrain-following_radar/xDMKDroW">terrain</a>. The term RADAR was coined in 1940 by the <a href="/facts/United_States_Navy/xYK0fUou">United States Navy</a> as an <a href="/facts/Acronym_and_initialism/nlHK7aRt">acronym</a> for "radio detection and ranging". The term radar has since entered English and other languages as an anacronym, a common noun, <a href="/facts/Acronym/nlHK7aRt">losing all capitalization</a>.
A radar system consists of a <a href="/facts/Transmitter/nFYghtKv">transmitter</a> producing <a href="/facts/Electromagnetic_wave/Ynx7ujCW">electromagnetic waves</a> in the <a href="/facts/Radio_spectrum/AP2frA1C">radio</a> or <a href="/facts/Microwave/HmVSN31Y">microwave</a> domain, a transmitting <a href="/facts/Antenna_(radio)/pGlcXBvc">antenna</a>, a receiving antenna (often the same antenna is used for transmitting and receiving) and a <a href="/facts/Radio_receiver/5olDTxkg">receiver</a> and <a href="/facts/Data_processing_system/1xeBseED">processor</a> to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving information about the objects' locations and speeds. This device was developed secretly for <a href="/facts/Military/kgNmLUnN">military</a> use by several countries in the period before and during <a href="/facts/World_War_II/2efV5L1U">World War II</a>. A key development was the <a href="/facts/Cavity_magnetron/8qd9pfsj">cavity magnetron</a> in the <a href="/facts/United_Kingdom/kuPAILt2">United Kingdom</a>, which allowed the creation of relatively small systems with sub-meter resolution.
The modern uses of radar are highly diverse, including air and terrestrial traffic control, <a href="/facts/Radar_astronomy/AJmcEDkl">radar astronomy</a>, <a href="/facts/Antiaircraft_warfare/fHtGQpLy">air-defense systems</a>, <a href="/facts/Close-in_weapon_system/dWyqWpBF">anti-missile systems</a>, <a href="/facts/Marine_radar/G5h3tyk0">marine radars</a> to locate landmarks and other ships, aircraft anti-collision systems, <a href="/facts/Research_vessel/7T7NsS7I">ocean surveillance</a> systems, outer <a href="/facts/Space_surveillance/CC3nQoUw">space surveillance</a> and <a href="/facts/Space_rendezvous/8KlcQyyf">rendezvous</a> systems, <a href="/facts/Meteorology/xblFr28q">meteorological</a> <a href="/facts/Precipitation/uq3nGQc8">precipitation</a> monitoring, <a href="/facts/Radar_remote_sensing/Mx4WmcpQ">radar remote sensing</a>, altimetry and <a href="/facts/Flight_control_system/4uBmYcHf">flight control systems</a>, <a href="/facts/Precision-guided_munition/9kX0Hy3y">guided missile</a> target locating systems, <a href="/facts/Self-driving_car/KXeFywXS">self-driving cars</a>, and <a href="/facts/Ground-penetrating_radar/5pUWHTfP">ground-penetrating radar</a> for geological observations. Modern high tech radar systems use <a href="/facts/Digital_signal_processing/PEG7azr8">digital signal processing</a> and <a href="/facts/Machine_learning/e0w0XJTu">machine learning</a> and are capable of extracting useful information from very high <a href="/facts/Noise_(electronics)/Izbv38Rr">noise</a> levels.
Other systems which are similar to radar make use of other parts of the <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a>. One example is <a href="/facts/Lidar/b9SPUmLM">lidar</a>, which uses predominantly <a href="/facts/Infrared_light/44XdJNcc">infrared light</a> from <a href="/facts/Laser/jk6PTvvT">lasers</a> rather than radio waves. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents.

Radar open-in-new

Radar