Analysis of antenna pointing errors on SAR image quality

Antenna beam pointing accuracy and stability are key issues for obtaining reliable and high quality remote sensing data in space-borne SAR sensors. A wide set of causes, related to technological aspects and environmental conditions acting at both bus and payload level, contribute to misalign the actual antenna bore sight from the theoretical direction. Even very small error angles on the yaw, pitch and roll axes directly reflect on antenna pointing, impacting on key image quality parameters such as resolution, swath width, signal to ambiguity ratio. Particularly, two major types of errors can be considered: time invariant (static) errors and time-variant (dynamic) errors. The different SAR image quality parameters show different sensitivity to mispointing and therefore are affected in different ways by satellite attitude. In this paper we analyze the effects of static and dynamic errors and we predict their impact of the most relevant SAR image quality parameters, by assuming as reference a generic X-band SAR mission.