TABLE OF CONTENTS What is radar?
What can it do?
How well can it do it?
A rough-and-ready guide to radar and its capabilities.
Radar is all about using radio waves to detect the presence of objects and to find their position. The word radar, first used by the US Navy in 1940, is derived from radio detection and ranging, thus conveying these two purposes of detection and location. Modern radar goes further and is being developed to classify or identify targets, and even to produce images of objects, for example mapping the ground from a satellite.
The principle of radar is that a transmitter sends out a radio signal, which will scatter off anything that it encounters (land, sea, ships, aircraft), and a small amount of the energy is scattered back to a radio receiver, which is usually, but not always, located near the transmitter. After amplification in the receiver, the signals are processed to sort out the required echoes from the clutter of unwanted echoes by a combination of both electronic signal processing and computer software (data processing).
There are many applications for radar, on scale sizes that vary from a few centimetres, such as the measurement of the thickness of furnace walls, to long-range systems probing planets across the solar system. Table 1.1 gives some idea of the variety of applications, and the list is growing as radar systems find their way into industry, homes and even the motor car.
