基于SAR成像的三维电磁散射特性反演方法的研究

发布时间：2018-02-09 18:34

本文关键词： 三维SAR成像电磁散射特性反演 RCS近远场变换　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：微波三维成像技术较传统的合成孔径雷达(SAR)成像技术可获得更丰富的信息,它能够准确地从背景噪声中分离出目标的空间位置及散射信息,有利于人们更加细致和精确地认识目标的三维散射系数的分布,适用于目标电磁散射特性的外场分析和研究。因而从三维SAR成像的角度研究目标的散射特性是目前的一个新兴的热门课题。本文以此为背景,通过分析三维SAR成像的电磁学机理,研究了基于SAR成像的三维近场电磁散射特性反演方法和基于SAR成像的三维电磁散射特性的近远场变换算法,可为基于三维SAR成像的RCS测量系统的研制提供一定的技术支持。本文主要工作如下:1.介绍了基于固定发射机的线阵三维SAR成像的系统模型,简要分析了该模型的三维分辨率,概述了线阵三维SAR成像原理;为满足三维SAR距离向高分辨需要,本文以步进频率(SF)信号作为发射信号,研究了三维后向投影(BP)成像算法、三维距离—多普勒(RD)成像算法和三维波数域成像算法,并利用FEKO软件进行了仿真实验,获得了汽车的三维高分辨SAR图像,验证了三种算法的有效性;然后通过实测和仿真实验简要探讨了三维SAR成像技术应用在RCS测量上的优势。2.研究了基于SAR成像的三维近场电磁散射特性反演方法。首先介绍了几个有关雷达目标散射特性的概念;然后由Stratton-Chu电场积分方程出发,从时域和频域两种角度分析了发射信号为步进频率信号时的三维SAR成像的电磁学机理,解释了三维SAR成像的物理含义,阐述了基于SAR成像的近场电磁散射特性反演的原理,提出了基于SAR成像的三维近场散射特性反演算法,通过仿真实验验证了算法的有效性;研究了系统测量误差和平台运动误差对反演精度的影响,并对误差产生的原因作了分析,为高精度散射特性的反演方法的研究奠定基础。3.重点研究了两种基于SAR成像的电磁散射特性近远场变换算法。首先,详细阐述了基于多散射中心模型的RCS近远场变换原理,给出了基于多散射中心模型的RCS近远场变换算法,通过仿真实验验证了该算法的有效性;然后,从成像的角度定量分析了基于多散射中心模型的RCS近远场变换的误差,为目标的高精度RCS反演打下基础;其次,详细阐述了基于目标表面电磁流模型的RCS近远场变换原理,给出了基于该模型的RCS近远场变换算法,通过仿真实验验证了该算法在复杂目标RCS近远场变换上的有效性;最后,对比分析了两种算法的优缺点。
[Abstract]:Compared with traditional synthetic Aperture Radar (SAR) imaging technology, microwave 3D imaging technology can obtain more abundant information, and it can accurately separate the spatial position and scattering information of the target from the background noise. It is helpful for people to have a more detailed and accurate understanding of the distribution of the three-dimensional scattering coefficients of the target, It is suitable for external field analysis and study of electromagnetic scattering characteristics of targets. Therefore, it is a new and hot topic to study the scattering characteristics of targets from the angle of 3D SAR imaging. By analyzing the electromagnetic mechanism of three-dimensional SAR imaging, the inversion method of three-dimensional near-field electromagnetic scattering characteristics based on SAR imaging and the near-far-field transform algorithm of three-dimensional electromagnetic scattering characteristics based on SAR imaging are studied. It can provide some technical support for the development of RCS measurement system based on 3D SAR imaging. The main work of this paper is as follows: 1. The system model of linear array 3D SAR imaging based on fixed transmitter is introduced, and the 3D resolution of the model is analyzed briefly. The principle of linear array 3D SAR imaging is summarized, and in order to meet the need of high resolution of 3D SAR range, this paper studies the algorithm of 3D backward projection SAR imaging with step frequency signal as the transmitting signal. Three dimensional range Doppler imaging algorithm and three dimensional wavenumber domain imaging algorithm are used in the simulation experiment with FEKO software to obtain the three dimensional high resolution SAR image of the automobile. The validity of the three algorithms is verified. Then, the advantage of 3D SAR imaging in RCS measurement is briefly discussed through actual measurement and simulation experiment. The inversion method of three-dimensional near-field electromagnetic scattering characteristics based on SAR imaging is studied. Firstly, several radar targets are introduced. The concept of scalar scattering property; Then, based on the Stratton-Chu electric field integral equation, the electromagnetic mechanism of 3D SAR imaging when the transmitted signal is a step frequency signal is analyzed from two angles of time domain and frequency domain, and the physical meaning of 3D SAR imaging is explained. In this paper, the principle of near-field electromagnetic scattering inversion based on SAR imaging is described, and a three-dimensional near-field scattering inversion algorithm based on SAR imaging is proposed. The effectiveness of the algorithm is verified by simulation experiments. The effects of system measurement error and platform motion error on the inversion accuracy are studied, and the causes of the errors are analyzed. This paper lays a foundation for the research of the inversion method of high precision scattering characteristics. 3. Two kinds of near far field transform algorithms of electromagnetic scattering characteristics based on SAR imaging are studied. Firstly, the principle of near far field transform of RCS based on multi scattering center model is described in detail. The near far field transform algorithm of RCS based on multi scattering center model is presented, and the validity of the algorithm is verified by simulation experiments, and then the error of RCS near far field transformation based on multi scattering center model is quantitatively analyzed from the point of view of imaging. It lays the foundation for high precision RCS inversion of the target. Secondly, the principle of RCS near-far field transformation based on the surface electromagnetic current model of the target is described in detail, and the RCS near-far field transform algorithm based on the model is presented. The effectiveness of the proposed algorithm in the near far field transformation of complex target RCS is verified by simulation experiments. Finally, the advantages and disadvantages of the two algorithms are compared and analyzed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.52

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