Radar
RADAR is an abbreviated word derived from 'radio detecting and ranging'. It is an electromagnetic sensor used for detecting, locating, tracking and identifying objects of various kinds at considered distance. It operates by transmitting electromagnetic energy towards objects, commonly referred to as targets, and observing the echoes returned from them. The targets may be aircraft, ships, spacecraft, automotive vehicles and astronomical bodies or even birds, insects and raindrops, Radar can not only determine the presence, location and velocity of such objects but can sometimes obtain their size and shape as well. What distinguishes radar from optical and infrared sensing devices is its ability to detect faraway objects under all weather conditions and to determine their range with precision. Radar underwent rapid development during the 1930s and 40s to meet the needs of the military. It is still widely employed by the armed forces and many advances in radar technology have in fact been subsidized by the military. At the same time, radar has found an increasing number of important civilian applications notably air traffic control, remote sensing of the environment, aircraft and ship navigation speed measurement for industrial applications and for the law enforcement, space surveillance and planetary observation.