As showni nF ig.1 ,a na ircraftc ar

As showni nF ig.1 ,a na ircraftc arries ana ntenna which illuminates a ground-swath parallel to the flight path; the radar beam is orientedi na zimuthr oughly normal to the direction of flight; at range r, the azimuth lineal beamwidth ,BY ism uchl argert hant hed esired azimuth resolution at that range. Finally, the radar is “coherent;” that is, the receiver has available a reference signal from which the transmitted signal was derived. Synthetic-aperturer adarsd eriver angei nformation through pulsing, and derive fine azimuth resolution by processing Doppler-shifted radar returns which lie in a spectral band which is adequately sampled by the pulse rate of the radar. For our purposes, we may neglect this intermediates ampling process and considero nlyt he reconstructed azimuth histories which are easily derived from the samples. We will assume that the entire radar receiver and processor behave as a linear system ; we can then investigate the response of the radar to a single “point” target,4 and by superposition extend the results to apply to realistic reflective complexes. To find the form of the signal returned to the radar antenna, consider a point target located at a position x1 along the ground track, at a range rl from the aircraft flight path (Fig. 2). Let a sinusoid of radian frequency w be transmitted