Matrix Pencil Method for Topography-Adaptive Digital Beam-Forming in Synthetic Aperture Radar

Abstract

Spaceborne Synthetic Aperture Radar (SAR) with Digital Beam-Forming (DBF) in elevation uses very sharp time-variant antenna beams to increase the Signal-to-Noise Ratio (SNR) and the Range Ambiguity to Signal Ratio (RASR). However, in acquisition scenarios of imprecisely known Earth topography the antenna pointing might be mismatched with the surface geometry. To handle this issue, it is suggested to apply pre-processing to DBF, which determines the angle of the incident echo signal on the planar antenna array. In this paper an innovative method is derived, which estimates the direction of arrival on the acquired raw-data with high accuracy and in real-time. The method is based on the matrix pencil, which is a common approach in mathematics for solving linear equation systems. As a key innovation this paper describes further improvements and adaptions to SAR scenarios and gives a possible concept of practical implementation. For proof of concept a series of different simulation tasks is performed.