Chapter III: What is radar?

Radar is a device which detects invisible or distant objects by means of reflected radio waves and is capable of locating them accurately in space. Radar can detect with the speed of light any object that will reflect its waves, whether in the sky, on the sea or on land. It can almost literally see by means of its radio waves, quite as the eye sees by means of light waves. More than that, it can detennine the object's range, that is, the distance to it in miles and yards with fantastic accuracy. Since the speed of the waves is a known constant, and since the radar receiver can measure, in millionths of a second, the time taken by the radiation from the radar's transmitter to reach the object and be reflected back, the distance can be determined in an inconceivable fraction of time, with accuracies measured in yards or even feet.