Wide-swath space-borne SAR using a quad-element array

The authors describe an array-based approach to increasing the swath width of spaceborne synthetic aperture radar beyond the limit normally imposed by ambiguity. The nulls of a quad-element rectangular array are used to suppress returns from range and azimuth ambiguities, allowing the swath to be increased by a factor of approximately four. A conceptual design is presented, based on ERS-1, that gives a swath extending from 250 km off nadir to over 700 km, with a blind region centred at 500 km. Some adaptive techniques for steering the nulls are discussed.