Radar is a short form of "Radio detection and ranging". In this instrument radio waves of very short wavelength are used to locate an enemy aircraft or ship. A concave transmitter mounted on a rotating platform sends radio waves in all directions. The radio waves on striking the aircraft or ship are reflected back. The reflected radio waves are received by a concave receiver, which is mounted at a small angle with the transmitter, On receiving the radio waves, the position of the enemy aircraft can be located on a monitor screen as a bright spot.