Elevation-Plane Multi-Antenna SAR
This chapter discusses elevation-plane multi-antenna synthetic aperture radar (SAR) for overcoming the fundamental tradeoff between swath width and range ambiguity. Various methods have been proposed to overcome this limitation. The use of array nulls to achieve wide-swath SAR imaging has been proposed. In this technique, which refer to as ‘null steering’, the pulse repetition frequency is increased for a higher azimuth resolution. The range ambiguities are controlled by steering the nulls of the receiving array at them. The receiving antenna is formed from an array of antennas, each has similar size as a conventional SAR antenna. When processing the null-steered SAR data, consideration must be given to the following two points. First, the element weights must be updated for each radar position. This is because the ambiguities of an imaging point remain at fixed positions on the terrain as the radar traverses the synthetic aperture. Second, the required element weights are different from each imaging point.