Radar is an acronym for “RAdio Detection And Ranging.” A radar installation emits electromagnetic waves and detects the waves reflected from an object. It measures the time for the “echo” to return to find the distance of the object. The radar dish is constantly rotating, permitting it to find the direction of the object as well. Radar is used in many different arenas, but was first used in World War II to detect the approach of enemy bombers.