SIGNAL PROPERTIES OF SPACEBORNE SQUINT-MODE SAR

This paper presents signal properties of spaceborne, strip-map SAR for very large squint angles. Doppler centroid, azimuth bandwidth, and ex posure time are derived in terms of the platform attitude and elevatio n angle, This allows a description of the Doppler centroid variation w ith range and terrain height, and explains a possible range dependence of azimuth bandwidth at high squint, The yaw and pitch required to mi nimize Doppler centroid and azimuth bandwidth variation are derived, a nd residual Doppler centroid variation in the presence of antenna poin ting errors is presented. The SAR constraint on the relationship betwe en swath width and azimuth bandwidth is revisited for high squint, and is used to present a fundamental limit on squint angle. Finally, proc essing considerations arising from the shape of the two-dimensional (2 -D) spectrum with high squint are discussed.