Antenna Pattern Modeling and Calibration for Spaceborne SAR Systems

Abstract

Synthetic aperture radar (SAR) systems acquire SAR images for manifold scientific and commercial remote sensing applications. A main part of the system, the SAR antenna, needs to be calibrated to deliver high-quality radar data products. For this purpose, novel methods are developed in this thesis involving an antenna model as the key element for the calibration of the system, which derives the antenna diagramms required for accurate image correction. The thesis emphasizes on the main aspects of this antenna pattern modeling and improvements on the antenna model approach: First, calibration and corrections terms applied on the antenna model are introduced, demonstrating the high accuracy of the model and resulting in significant simplifications for SAR system calibration. Second, the optimization of the antenna patterns in order to improve the image quality is described. A new system representation and its effect on image performance is derived and verified. Finally, a novel self-calibration approach is developed which improves the antenna model accuracy beyond the current specifications. Nominal acquisitions can be utilized to calibrate the antenna model and monitor its performance, eliminating the necessity of dedicated measurements over reference targets like rain forest. This makes the antenna model a key feature even for future SAR systems.