Constant-Time-Delay Interferences In Near-Field SAR: Analysis And Suppression In Image Domain

TL;DR

This paper analyzes and suppresses near-field SAR interferences with constant-time-delay features, introducing an analytical model and a low-rank reconstruction method to improve imaging quality.

Contribution

It presents the first analysis and suppression method for near-field SAR interferences, addressing a gap in existing far-field-focused techniques.

Findings

Interferences from nadir points and antenna coupling have constant-time-delay features.

The proposed method effectively suppresses interferences in near-field SAR images.

Analytical model accurately characterizes interference patterns in multiple dimensions.

Abstract

Inevitable interferences exist for the SAR system, adversely affecting the imaging quality. However, current analysis and suppression methods mainly focus on the far-field situation. Due to different sources and characteristics of interferences, they are not applicable in the near field. To bridge this gap, in the first time, analysis and the suppression method of interferences in near-field SAR are presented in this work. We find that echoes from both the nadir points and the antenna coupling are the main causes, which have the constant-time-delay feature. To characterize this, we further establish an analytical model. It reveals that their patterns in 1D, 2D and 3D imaging results are all comb-like, while those of targets are point-like. Utilizing these features, a suppression method in image domain is proposed based on low-rank reconstruction. Measured data are used to validate the correctness of our analysis and the effectiveness of the suppression method.