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基于新型积分方程的三维介质目标的电磁散射特性分析
【作者】 安宁；
【作者基本信息】 南京理工大学 ， 电磁场与微波技术， 2008， 硕士
【摘要】 复杂目标电磁散射的高效求解对于雷达系统设计与雷达目标识别具有十分重要的意义。如何准确、快速地分析三维复杂目标的电磁特性,长期以来一直是计算电磁学领域的研究重点。以矩量法(MOM)为基础的快速多极子方法(FMM)和多层快速多极子(MLFMA)的提出和实现,克服了经典高频方法的局限,使复杂电大尺寸目标的电磁散射特性分析成为可能。然而这些方法都是建立在均匀空间模型的基础上,即没有考虑周围环境因素的影响,所以在考虑目标体处于半空间环境下更有实际意义。本文的研究工作正是基于上述的工程应用背景下展开的,将目前较为成熟的均匀空间电磁场求解的各种算法扩展到半空间背景中,不但对半空间格林函数的表达和求解进行了研究,还考虑了各种环境因素对目标辐射特性或目标散射特性的影响,使目标与环境一体化高效建模成为可能。其次,本文对传统积分方程(PMCHWT)进行了改进,深入研究了一种新型的积分方程(JMCFIE),得到了具有良好性态的阻抗矩阵,从而加速了对半空间三维目标电磁特性数值计算的速度。同时Müller方程的应用,有效的解决了低频崩溃问题,一系列算例证明了此方法的可靠性。在此基础上,本文还对手征媒质的电磁特性进行了研究,一些数值计算结果的给出,验证了此方法的正确性与有效性,使其具有一定的实际意义和工程应用价值。
【Abstract】 To realize efficient solution of electromagnetic(EM) scattering from complex target has very practical value for the design of radar system and identify of radar target. The electromagnetic scattering of 3 D complex targets has attracted much more attention in engineering applications.Recently,intensive investigations have been done to find fast and accurate numerical methods to solve such problems.The FMM and MLFMA are applied to analyze the electromagnetic scattering and radiation of electrical-large targets which overcomes the limitation of conventional high frequency method.But those methods are all based on free space that leads to neglect some important factors.So it will have more significance that considering objects modeled in half-space.Based on these engineering application background,the research work realize a simple extension the free space algorithms to the half-space cases.The work not only investigates the expression and solution of half-space green’s function, but also considers lots of different environment factors which can affect electromagnetic scattering and radiation of targets.In addition,a new integral function named JMCFIE is presented which improves the conventional PMCHWT integral function.The new integral function can essentially improve characteristic of impedance matrix and accelerate iterative converging.At the same time,the Müller function is applied for overcoming the low frequency breakdown.The JMCFIE integral function is implemented in analyzing the electromagnetic characteristic of chiral object.The numerical examples show the accuracy and efficiency of the methods proposed in the dissertation.