Squint Angle Limitations for Space-Borne Spot SAR Imaging

Spot imaging at large squint angles is limited by the imaging time; and improving the azimuth resolution may limit the available squint angles. This is due to range migration during the coherent time and its effect on the receive window of the radar. As the need for higher resolution space borne SAR increases, the effect of the squint limitations on the system performance must be taken into consideration. This paper analyses the effect of system parameters on the available squint angles. Reserved Time is defined as the time in which the receive window migrates during the synthetic time. The Reserved time and receive window durations are expressed as functions of the squint angle and constant parameters of the problem; and the limits on the squint angles are presented. The derivation is done for Matched Filter processing. This paper defines the maximum allowed squint angle and it shows that beyond this limit, imaging is no longer possible.