Matrix Pencil Method for Direction of Arrival Estimation in DBF-SAR

Abstract

Synthetic Aperture Radar (SAR) satellites with Digital Beam-Forming (DBF) on receive form a narrow synthesized antenna beam, which traces the echo signal travelling along the Earth’s surface. This can be achieved by using the known geometrical relation between radar and ground. However, in presence of topography, this geometrical relation is distorted with reference to a spherical Earth model and the resulting mis-pointing of the antenna will lead to a loss of gain. As solution, this paper introduces an algorithm, which estimates the angle of the arriving echo signal before DBF in real-time with high accuracy to enable topography adaptive DBF. Especially for SAR, this matrix pencil method outperforms the results achieved with existing spectral estimation algorithms, such as MUSIC or ESPRIT.