TOPS Imaging Mode: Data-based Estimation of Antenna Pointing and Azimuth Steered Antenna Pattern

In this paper two issues concerning the antenna mis-pointing and the antenna pattern estimation for the TOPS imaging mode are presented. Both analyses require a demodulation of the raw data spectrum to account for the effect of azimuth antenna beam steering. A sensitivity analysis of this deramping function as well as results of the antenna mis-pointing and Doppler centroid estimation using TerraSAR-X TOPS data are presented. A second approach investigated in this paper is the possibility to estimate the two-way azimuth antenna pattern using data acquired over homogeneous areas, e.g., rainforest, such that no specific ground equipment, like transponders, is required. However, this method requires certain instrument capabilities and is only feasible for analysis of the 3dB-beam width of the steered antenna pattern. Exemplary results are shown with TerraSAR-X data