RCS Calculation based on Near-Field L1-Regularized SAR Imaging

The measurement accuracy of radar cross section (RCS) based on radar image is usually affected by the image quality. The sidelobe and clutter in the image will reduce the accuracy of RCS measurement. In order to solve the problem, a RCS measurement method based on near-field L1 regularized three-dimensional (3D) synthetic aperture radar (SAR) imaging is proposed. Compared with the traditional matched filtering (MF) method, L1-regularization method can effectively improve the quality of 3D SAR image, such as clutter and sidelobe suppression. Firstly, the near-field echo is processed by MF to obtain the three-dimensional image of the scene. Then, an L1-regularization technique based on 3D SAR image is used to suppress the sidelobe and clutter. Next, the far-field compensation factor is used to obtain the far-field RCS of the target. Finally, the simulation results show that the proposed method can effectively improve the image quality and RCS measurement accuracy.

1. Introduction

Radar cross section (RCS) is an important physical quantity to evaluate the scattering ability of radar target to irradiate electromagnetic wave [1]. With the development of modern stealth technology, it is necessary to accurately measure the RCS of the target to verify the stealth performance of the target [2]. The primary requirement of traditional RCS measurement is the far-field condition, , D is the maximum physical size of the target and is the wavelength [3]. The larger the size of the target and the higher the frequency of the transmitted signal, the longer the test distance between the radar and the target is required. Therefore, in the actual measurement, the far-field condition is difficult to meet. Indoor measurement is usually carried out in microwave anechoic chamber by special equipment (such as compact range equipment). But the cost is expensive and RCS measurement for large-scale targets is also difficult. The frequency range of single paraboloid application is limited and the static field range is small, so it is difficult to measure the electromagnetic scattering characteristics of large-scale targets [4]. To solve the problem of test range, RCS feature extraction method based on near-field radar image is proposed. These methods are divided into RCS feature extraction based on synthetic aperture radar (SAR) imaging and RCS feature extraction based on inverse synthetic aperture radar (ISAR) imaging [5]–[7]. In this paper, SAR technology is used to obtain near-field target scene echo.