迭代MEI算法及其在多导体柱散射中的应用

本文提出了适于分析任意截面形状多导体柱散射问题的迭代ＭＥＩ算法。迭代ＭＥＩ算法充分利用了ＭＥＩ方程的不变性特点，不仅使得截断边界十分贴近散射体表面，节省内存单元；而且ＭＥＩ系数可重复利用，从而大大减少了计算量。文中与已有结果作了深入比较，取得了很好的一致性，并突破了已有算法在尺寸上的限制，给出了电大尺寸多柱体的计算结果。     

迭代MEI算法及其在媒质涂敷多柱体散射中的应用

本文提出了分析媒质涂敷多导体柱散射问题的迭代ＭＥＩ算法。新的迭代过程与ＭＥＩ方法结合，充分利用了ＭＥＩ方程的不变性特点，可重复利用ＭＥＩ系数，不仅节省内存单元，而且大大减少了计算量。该方法较以往多柱体散射问题仅局限于小尺寸导体柱或均匀介质柱情况有很大改进。本文计算结果与已有结果吻合很好，并给出了电大尺寸媒质涂敷多柱体的计算结果。     

一种有效的数值吸收边界条件与MEI方法的比较

本文给出了一种新的吸收边界条件，并与不变性测试方程法（ＭＥＩ）、矩量法在计算时间、存贮空间方面进行比较，结果表明运用这个条件在计算时间和存贮空间上都具有优点，是计算电大尺寸媒质柱体电磁散射特性的一种有效手段。     

不规则地形散射场的MEI方法分析

本文将非均匀、不规则的地形处理成阻抗表面，沿地形表面作共形网格剖分，并利用不变性测试方程法（ＭＥＩ方法），使截断边界进一步靠近地表，从而减少计算机内存的占用量，使对实际工程中遇到的电大尺寸地形的分析及研究成为可能，文中计算的电大尺寸达１８０个波长。本文对比了不同电尺寸和地形结构的散射和传播特性计算，并给出几个实用模型的计算结果。     

用MEI—FD方法分析Chiral媒质的电磁散射问题

本文应用不变性测试方程和有限差分方法分析Ｃｈｉｒａｌ媒质的电磁散射问题。应用该方法时，要在所讨论的区域内建立起一组有关电场和磁场的耦合差分方程，并且要在截断边界上应用不变性测试方程建立起有关边界点系数的方程。文中给出了一些非均匀、有耗且具有电大尺寸任意横截面Ｃｈｉｒａｌ柱的雷达散射截面的数值结果。     

用MEI—FD方法分析Chiral媒质的电磁散射问题

本文应用不变性测试分程和有限差分方法分析Ｃｈｉｒａｌ媒质的电磁散射问题。应用该方法时，要在所讨论的区域内建立起一组有关电场和磁场的耦合差分方程，并且要在截断边界上应用不变性测试方程建立起有关边界点系数的方程。文中给出了一些非均匀、有耗且具有电大尺寸任意横截面Ｃｈｉｒａｌ柱的雷达散射截面的数值结果     

频域Mur条件差分近似的构造和应用

本文构造了Ｍｕｒ条件的频域有限差分近似。结果推导的非均匀、各向异性媒质中有限差分方程，可以有效、方便地计算电大尺寸复杂质体的电磁散射问题。     

电大尺寸导体柱电磁散射问题的快速算法

引入Ｍｕｒ边界条件建立有限差分方法,结合快速算法计算电大尺寸导体柱的电磁散射问题,避免了计算ＭＥＩ系数的计算瓶颈,且差分方程系数矩阵的生成、求解时间以及占用内存均与柱体表面剖分点数呈线性关系,极大的缩短了总的计算时间。所得结果与其他方法相比具有较好的一致性。     

快速MEI算法及其在电大尺寸电磁散射问题中的应用

本文基于不变性测试方程法（ＥＭＩ）提出一种快速算法,在二维散 表面建立菜形差分网格后,通过对节点的重新排序,将原问题中的稀疏矩阵变换为带状稀疏阵,从而使占用的计算机内存和计算时间均由Ｏ（Ｎ２）下降为Ｏ（Ｎ）,可以解决原来无法计算的问题,议事 成功地计算了最大周长为１００００个波长的几个电大尺寸二维柱体的电磁散射,并与矩量法、ＭＥＩ方法进行比较。     

时域MEI方法初探

对时域ＭＥＩ方法进行了初步探索,根据ＭＥＩ方法的基本原理,建立起时域ＭＥＩ方法的一阶吸收边界条件,应用该条件对线源辐射问题的数值实验和研究表明,它可使截断边界离源更近,同时也证实了时域ＭＥＩ方法的可靠性和精确性。     

任意截面形状电大尺寸涂覆介质导体柱电磁散射特性的分析

本文借助不变性测试方程这一新概念，成功地计算了任意截面形状电大尺涂覆介质导体柱的电磁散射特性。     

一种有效的吸收边界条件及其在散射问题中的应用

本文推导了非均匀各向异性媒质的有限差分方程,通过改变参数可以使该差分方程适用于均匀、非均匀、各向同性或各向异性等各种情况下柱体的散射计算.文中还给出了一种新的吸收边界条件,并与不变性测试方程法和矩量法在计算时间、存贮空间方面进行了比较.结果表明:运用这个条件在计算时间和存贮空间上都具有优点,是计算电大尺寸媒质柱体电磁散射特性的一种有效手段.     

Iterative boundary condition (IBC) in finite difference solvingscattering problems of open region

A novel truncation boundary condition, the iterative boundary condition (IBC), is proposed for finite difference (FD) solving electromagnetic scattering problems. The iterative process of this condition is given. Solutions of the IBC for some 2D cylinder scattering problems have been obtained and are compared with solutions using MoM and MEI. These solutions show very good agreement     

The Concept of Exterior Interactions for Electromagnetic Metrology

The paper deals with the further development of the concept of practical applications of electromagnetic interactions between the exterior fields of open slot lines and resonators with the boundary layers of physical media, dielectric materials, and coatings. Theoretical justification has been provided and a quickly converging algorithm has been built for the analysis of a characteristic equation describing the electromagnetic interaction of a longitudinal-slot cylinder and interface of two media. Spectral characteristics of the system have been presented for some types of real functional materials.     

Complex frequency shifted-perfectly matched layer for the finite-element time-domain method

We present a new formulation to implement the complex frequency shifted-perfectly matched layer (CFS-PML) for boundary truncation in three-dimensional vector finite-element time-domain method applied to the vector wave equation. It is shown that the proposed method is highly absorptive to evanescent modes, when computing the wave interaction of elongated structures or sharp corners, and can improve the performance of the boundary truncation, significantly. The impact of the CFS-PML parameters on the reflection error is investigated and optimal choices of these parameters are derived.     

任意截面非均匀各向异性阻抗柱体的电磁散射

采用矩量法(MoM)结合阻抗边界条件研究了二维无限长任意形状截面非均匀各向异性阻抗柱体的电磁散射特性。散射场通过Stratton-Chu电场积分方程、电流连续性方程和二维格林函数予以求解。当柱体截面矢径的模等于恒定值时,目标退化为二维无限长圆柱,提出的计算方法仍然有效。计算得到的散射宽度结果与解析法、物理光学法(PO)的结果进行了比较,吻合良好。     

FEM/BEM混合法计算各向异性不均匀介质柱电磁散射

应用有限元-边界元(FEM/BEM)混合法计算二维各向异性不均匀介质柱电磁散射,对介质柱内、外区域分别采用有限元和边界元法进行分析,然后应用边界条件建立部分稀疏部分满填充的矩阵方程.应用内观法结合多波前法求解该矩阵方程,分别计算了均匀分布和不均匀分布的各向异性介质柱的雷达散射截面.数值计算表明,有限元-边界元混合法在分析和计算不均匀开放域电磁问题时有一定的优势.     

Extended integral equation formulation for scattering problems froma cylindrical scatterer

An extended integral equation is developed for electromagnetic scattering from a perfectly conducting cylinder and a dielectric cylinder. The conventional surface integral equations cannot yield unique solutions when the wavenumber of the electromagnetic wave is equal to an eigenwavenumber of the system. Several methods to overcome this difficulty have been presented, but each method includes some drawbacks. A numerical method is proposed in which the boundary element method is applied to the extended integral equations with the observation points lying on a closed surface inside the scatterer. It is shown that the extended integral equations have unique solutions for any given wavenumber. As examples, plane wave scattering from a perfectly conducting elliptic cylinder, a dielectric elliptic cylinder, and a dielectric rectangular cylinder is numerically analyzed     

Finite-element solution to electromagnetic scattering problems bymeans of the Robin boundary condition iteration method

A new numerical method, called the Robin boundary condition iteration (RBCI), is proposed for the finite-element (FE) solution of electromagnetic scattering problems in open boundary domains. The unbounded domain is truncated to a bounded one by means of a fictitious boundary that contains the scatterer and on which a suitable nonhomogeneous Robin (mixed) boundary condition is assumed for the Helmholtz equation in the bounded domain. The Robin condition is expressed by means of an integral formula (the second Green identity) in terms of the field in the interior of the bounded domain, with the integration surface being a surface strictly enclosed by the truncation boundary. The discretized differential and integral equations are then coupled together to solve the problem. The formulation is completely immune from the well-known interior resonance problems. A simple and effective iterative solving scheme is described. Examples are also provided to validate RBCI and compare it with other methods     

涂覆各向异性复合手征介质的阻抗圆柱体的雷达截面积

本文解决了平面波入射时涂覆各向异性复合手征介质的阻抗圆柱体的电磁散射问题。首先推导得到各向异性复合手征介质层中电磁场量的基本方程;然后根据边界条件得出计算所讨论的阻抗圆柱体的雷达散射截面的解析表达式。文中还给出若干数值结果。