The radar is utilised as an aid in the field of marine and aerial navigation. It was developed in Great Britain in the late 1930's. The word radar is an acronym for Radio Detection And Ranging. It operates by transmission of microwave pulses and the detection of their echoes. With the use of an aerial these echoes can be received and the microwave pulses discharged. The time which elapses between transmission of the pulse and the reception of its echo, determines the distance to the object causing the echo. The given result is displayed on a radar screen, as a spot or `blip.' The radar screen consists of a cathode ray tube, very similar to those found in television receivers.
