1.1 Radar Functions and Applications

The two most basic funsctions of radar are inherent in the word, whose letters stand for RAdio Detection And Ranging. Measurement of target angles has been included as a basic function of most radars, and Doppler velocity is often measured directly as a fourth basic quantity. Discrimination of the desired target from background noise and clutter is a prerequisite to detection and measurement, and resolution of surface features is essential to mapping or imaging radar.

The block diagram of a typical pulsed radar is shown in Fig. 1.1. The equipment has been divided arbitrarily into seven subsystems, corresponding to the usual design specialties within the radar engineering field. The radar operation in more complex systems is controlled by a computer with specific actions initiated by a synchronizer, which in turn controls the time sequence of transmissions, receiver gates and gain settings, signal processing, and display. When called for by the synchronizer, the modulator applies a pulse of high voltage to the radio frequency (RF) amplifier, simultaneously with an RF drive signal from the exciter. The resulting high-power RF pulse is passed through transmission line or waveguide to the duplexer, which connects it to the antenna for radiation into space. The antenna shown is of the reflector type, steered mechanically by a servo-driven pedestal. A stationary array may also be used, with electrical steering of the radiated beam. After reflection from a target, the echo...