發(fā)布時間：2018-02-09 18:34

  本文關鍵詞： 三維SAR成像 電磁散射特性反演 RCS近遠場變換　出處：《電子科技大學》2014年碩士論文　論文類型：學位論文

【摘要】：微波三維成像技術(shù)較傳統(tǒng)的合成孔徑雷達(SAR)成像技術(shù)可獲得更豐富的信息,它能夠準確地從背景噪聲中分離出目標的空間位置及散射信息,有利于人們更加細致和精確地認識目標的三維散射系數(shù)的分布,適用于目標電磁散射特性的外場分析和研究。因而從三維SAR成像的角度研究目標的散射特性是目前的一個新興的熱門課題。本文以此為背景,通過分析三維SAR成像的電磁學機理,研究了基于SAR成像的三維近場電磁散射特性反演方法和基于SAR成像的三維電磁散射特性的近遠場變換算法,可為基于三維SAR成像的RCS測量系統(tǒng)的研制提供一定的技術(shù)支持。本文主要工作如下:1.介紹了基于固定發(fā)射機的線陣三維SAR成像的系統(tǒng)模型,簡要分析了該模型的三維分辨率,概述了線陣三維SAR成像原理;為滿足三維SAR距離向高分辨需要,本文以步進頻率(SF)信號作為發(fā)射信號,研究了三維后向投影(BP)成像算法、三維距離—多普勒(RD)成像算法和三維波數(shù)域成像算法,并利用FEKO軟件進行了仿真實驗,獲得了汽車的三維高分辨SAR圖像,驗證了三種算法的有效性;然后通過實測和仿真實驗簡要探討了三維SAR成像技術(shù)應用在RCS測量上的優(yōu)勢。2.研究了基于SAR成像的三維近場電磁散射特性反演方法。首先介紹了幾個有關雷達目標散射特性的概念;然后由Stratton-Chu電場積分方程出發(fā),從時域和頻域兩種角度分析了發(fā)射信號為步進頻率信號時的三維SAR成像的電磁學機理,解釋了三維SAR成像的物理含義,闡述了基于SAR成像的近場電磁散射特性反演的原理,提出了基于SAR成像的三維近場散射特性反演算法,通過仿真實驗驗證了算法的有效性;研究了系統(tǒng)測量誤差和平臺運動誤差對反演精度的影響,并對誤差產(chǎn)生的原因作了分析,為高精度散射特性的反演方法的研究奠定基礎。3.重點研究了兩種基于SAR成像的電磁散射特性近遠場變換算法。首先,詳細闡述了基于多散射中心模型的RCS近遠場變換原理,給出了基于多散射中心模型的RCS近遠場變換算法,通過仿真實驗驗證了該算法的有效性;然后,從成像的角度定量分析了基于多散射中心模型的RCS近遠場變換的誤差,為目標的高精度RCS反演打下基礎;其次,詳細闡述了基于目標表面電磁流模型的RCS近遠場變換原理,給出了基于該模型的RCS近遠場變換算法,通過仿真實驗驗證了該算法在復雜目標RCS近遠場變換上的有效性;最后,對比分析了兩種算法的優(yōu)缺點。
[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.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN957.52

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本文編號：1498588