基于三维SAR成像的RCS近远场变换方法研究

Research on Methods of Targets' RCS Near-field-to-far-field Transformation Based on 3-D SAR Imaging

微波3维成像能够准确地从背景噪声中分离出目标的散射信息,适用于外场目标电磁(EM)散射特性的分析和研究,因而从3维合成孔径雷达(SAR)成像的角度研究目标电磁的散射特性是目前的一个新兴的热门课题。该文以此为背景,首先从Stratton-Chu积分方程出发详细推导3维SAR的近场波数域成像过程,解释3维SAR成像的物理意义;然后阐述基于3维SAR成像的雷达散射截面积(RCS)近远场变换原理,介绍3维SAR图像的散射中心提取方法,给出基于3维SAR成像的RCS近远场变换算法;最后通过FEKO软件进行了仿真实验,得到了5个点目标的RCS近远场变换的方位特性曲线和频率特性曲线,并通过与理论情况的对比,验证该算法在RCS近远场变换技术中的有效性。

Microwave 3-D imaging technique can accurately separate and extract the attractive targets from the background noise. So it can be utilized to analyze and study the Electro Magnetic（EM） scattering characteristics of the outfield targets. Thus researching the EM scattering characteristics of targets from the perspective of 3-D SAR imaging is becoming an emerging hot field. Based on the background above, firstly, the near field 3-D imaging process in wave-number domain is deduced from the Stratton-Chu integral equation and the physical meaning of 3-D SAR imaging is explained. Then, the principle of targets＇ Radar Cross Section（RCS） Near-Field-to-Far-Field Transformation（NFFFT） based on 3-D SAR imaging is elaborated and the method of scattering center extraction from 3-D SAR image is introduced and the algorithm of targets＇ RCS NFFFT based on 3-D SAR imaging technique is presented. Finally, though some experiments using the FEKO software, five scattering points＇ observing angle characteristic curve and frequency characteristic curve are gotten. Through the comparative experiments with the ideal situation, the effectiveness of the RCS NFFFT algorithm is validated.