半空间环境下复杂旋转对称体电磁散射特性的分析

【作者】 梁洪灿；

【导师】 陈如山；

【作者基本信息】 南京理工大学 ， 电磁场与微波技术， 2009， 硕士

【摘要】 利用轴对称性可以将电大的旋转对称体电磁问题转化为求解每个具有小规模矩阵方程的问题,即原问题的Fourier模式,从而可以大大提高计算效率,并且减少内存需求。本文发展了旋转对称体矩量法来快速有效地分析半空问环境下复杂旋转对称体的电磁散射特性。本文研究了介质旋转对称体在半空间环境下的散射问题。首先通过麦克斯韦方程、辅助位函数、等效原理和边界条件建立了电、磁流的混合场积分方程(Poggio-Miller-Chang-Harrington-Wu,PMCHW);在外部等效积分中引入了并矢格林函数,它的计算是通过离散复镜像方法来实现的。然后再利用旋转对称性,将等效流(等效电流、磁流)展开为关于φ的傅立叶级数形式和关于,的分段函数形式。最后运用矩量法求得每个Fourier模式矩阵方程的解。因为各傅立叶模式之间存在正交性,可以分别计算单个独立模式下的等效流,再进行线性叠加,这样就大大减少了未知量个数和计算时间。本文还进一步研究了含有均匀手征媒质的旋转对称目标在自由空间以及半空间环境下的电磁散射特性。利用了等效原理、边界条件和手征媒质中波的分解技术,在手征物体表面建立了关于等效电、磁流的PMCHW方程,然后运用矩量法同介质旋转对称体类似求解。最后给出了一些典型数值算例,表明了本文所发展的旋转对称体矩量法对分析含有手征媒质目标的电磁散射特性具有很好的准确性和很高的计算效率。更多还原

【Abstract】 The usage of the axisymmetric property of the body of revolution(BoR) can translate an original electrically large BoR-problem into a series problems with small size of matrix equations,namely a Fourier mode of the original one,which can greatly improve the computational efficiency and reduce the memory requirements.In this thesis,the accurate and efficient analyses of electromagnetic scattering of complex BOR above half space has been realized by the development of method of moments for BOR.This paper mainly researches electromagnetic scattering from dielectric bodies of revolution above a lossy half space.A set of Poggio-Miller-Chang-Harrington-Wu (PMCHW) are formulated via Maxwell’s equations,potential functions,equivalent principle and the boundary conditions.Introducing the dyadic Green’s functions of exterior equivalent integral equations are computed by the discrete complex image method.With the rotational symmetry,the unknown equivalent surface currents(electric currents and magnetic currents) can be expanded in Fourier series inφand sectional function in t.Finally,a solution of each Fourier model matrix equation is solved by the methods of moment.Because each mode is orthogonal to the others,the problem can be solved under each mode respectively and each solution is summed up subsequently.Thus it reduces greatly the sum of unknown variable and the calculational time.The problem of electromagnetic scattering from homogeneous chiral BOR in free space and above a lossy half space is further studied in this thesis.A set of PMCHW for the unknown equivalent electric and magnetic currents on the chiral BOR’s surface are formulated,it is based upon using equivalent principle,the boundary conditions and the technique of wave decomposition.The PMCHW is solved using the method of moments in a formulation as the problem of dielectric BOR.Finally,the accuracy and efficiency of the methods proposed in this thesis has been validated by some representative numerical results.更多还原