Radar is a device to detect the aeroplane in the sky and to measure its distance from the radar station. Radar works on the principle of reflection of echo.
In radar, radio waves (signals) are transmitted from the transmitter antenna. These waves are reflected back after striking the aeroplane.
The reflected waves are received by the receiver through antenna. The time elapsed between the moment of transmission of waves and the reception of reflected waves (echo) is noted. Let it be t. Here t = 3 x 108 ms-1 is the speed of radio waves,then the distance of the aeroplane is given by
d = c x t/2.
