TerraSAR-X Azimuth Antenna Steering and Antenna Pointing Geometry

Abstract

The purpose of this report is to describe the TerraSAR-X antenna pointing geometry, especially w.r.t. the azimuth steering angle and the pointing accuracy. The azimuth steering angle is related to the squint angle. This means that the pointing accuracy directly translates into a squint angle error and therefore also into a Doppler centroid inaccuracy. Therefore the azimuth steering angle is evaluated w.r.t. to the TerraSAR-X azimuth reference antenna patterns and w.r.t. the calculated antenna pointing vector. The deviations are discussed. The pointing vector is necessary to find the intersection with the used earth model and finally to determine the satellite slant range geometry. From this geometry, parameters like e.g. the Doppler centroid or the B-parameter can be derived.