Influence of beam stepping control and pointing deviation on image quality of spaceborne sliding spotlight SAR

Abstract

Sliding spotlight mode is widely used in spaceborne SAR to achieve high resolution. However, due to the difficulty for antenna beam to scan continuously, it usually works by step scanning, which leads to paired-echo in SAR images. Meanwhile, the pointing of the antenna often deviates from the preset value when scanning, resulting in an increase in the amplitude of the paired echo. This paper works on the effect of beam stepping control and pointing deviation on image quality of Ka band spaceborne sliding spotlight SAR. Firstly, the azimuth echo signal in sliding spotlight mode under the beam stepping control and pointing deviation is modeled. Then, the influence of beam stepping control and pointing deviation is analyzed by using the paired-echo theory, and the quantitative relationship between beam granularity and pointing deviation and paired-echo is presented. Finally, the validity of the theoretical analysis is verified by computer simulation. The method in this paper provides a reliable basis for the design of parameters in spaceborne sliding spotlight SAR system.