Optimizing azimuth antenna steering: beyond TOPSAR

The paper focuses on the limits of the performances of TOPSAR acquisition mode, in terms of image quality and particularly to signal to ambiguity ratio (DTAR). These limits are due to the unwanted antenna pattern side-lobes arising when the antenna beam is steered in azimuth. Some ideas that could be exploited to limit the effect of grating lobes on DTAR are discussed. Particularly, a novel acquisition mode, TOPS-SPOT mode, or TUCANSAR, is presented. This is an enhancement of TOPSAR mode, featuring a non linear antenna beam steering law, that allows limiting the maximum squint, thus significantly reducing the effect of antenna grating lobes.