Radar is a detection system which uses radio waves to determine object range, angle, or velocity. Aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain can be detected with it. A radar system consists of a transmitter producing electromagnetic waves in the domain of radio or microwaves, a transmitting antenna, a receiving antenna (often used to transmit and receive the same antenna), and a receiver and processor to determine the properties of the object(s). Radio waves (pulsed or continuous) from the transmitter reflect the object and return to the receiver, and provide information about the location and speed of the object.During the time before and during World War II, Radar was created secretly for military use by many countries. A major invention was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small, sub-meter resolution systems. In 1940 the United States Navy coined the term RADAR as an acronym for RAdio Detection And Ranging.The term radar has since entered English and other languages as a common noun, losing all capitalization. Also suggested during RAF RADAR courses in 1954/5 was the following derivation: in Yatesbury Training Camp: Radio Azimuth Direction And Ranging. Modern radar uses include air and terrestrial traffic control, radar astronomy, air defense systems, missile systems, marine radars for locating landmarks and other ships, aircraft collision control systems, ocean surveillance systems, outdoor space surveillance and rendezvous systems, meteorological precipitation monitoring, altimeter and flight control systems, guided misuse