Author Description

The word radar is an acronym derived from the phrase RAdio Detection And Ranging and applies to electronic equipment designed for detecting and tracking objects (targets) at considerable distances. The basic principle behind radar is simple - extremely short bursts of radio energy (traveling at the speed of light) is transmitted, reflected off a target and then returned as an echo. Radar makes use of a phenomenon we have all observed, that of the ECHO PRINCIPLE. To illustrate this principle, if a ship's whistle were sounded in the middle of the ocean, the sound waves would dissipate their energy as they traveled outward and at some point would disappear entirely. If, however, the whistle sounded near an object such as a cliff some of the radiated sound waves would be reflected back to the ship as an echo. The form of the electromagnetic signal radiated by the radar depends upon the type of information needed about the target. Radar, as designed for marine navigation applications, is pulse modulated. Pulse-modulated radar can determine the distance to a target by measuring the time required for an extremely short burst of radio-frequency (r-f) energy to travel to the target and return to its source as a reflected echo. Directional antennas are used for transmitting the pulse and receiving the reflected echo, thereby allowing determination of the direction or bearing of the target echo.