三维大纵横比目标散射的快速精确求解

采用积分方程法严格求解三维大纵横比目标的电磁散射。在积分方程法的迭代求解中用快速我极子法（ＦＭＭ）加速矩阵与矢量的相乘计算,同时运用快速傅里叶变换（ＦＦＴ）进一步提高快速多极子方法中的转换预计算,数值结果表明：这种快速多极子法－快速傅立叶变换方法（ＦＭＭ－ＦＦＴ）特别适合于三维大纵横比目标的散射求解。     

一种旋转对称涂覆导体电磁散射高效分析方法

为改善传统方法分析旋转对称涂覆导体电磁散射问题的效率,提出了一种高效分析方法.该方法在介质表面建立电磁流混合场积分方程(Electric and Magnetic Current Combined Field Integral Equation,JMCFIE),在导体表面建立混合场积分方程(Combined Field Integral Equation,CFIE),利用了旋转对称体在空间上的旋转周期性,只需要对表面的母线进行剖分,具有未知量少且阻抗矩阵条件数好的特点.根据等效原理与边界条件推导了JMCFIE-CFIE方程,并与传统的PMCHW-CFIE方法对比了求解效率.数值算例表明该方法能明显改善方程的收敛性.     

低掠角入射动态分形粗糙海面与船目标的双站散射数值模拟

为快速数值计算动态粗糙分形海面上有船目标时的双站散射，该文将广义前后向迭代法（GFBM）与谱积分加速算法（SAA）结合用于求解磁场积分方程（MFIE）。避免了电场积分方程（EFIE）数值计算的不稳定性。数值模拟了TE锥形波低掠角入射在一维动态分形粗糙导体海面以及船目标存在时的双站散时，讨论了多次散射传播的双疲散射与动态分形海面和船目标特征参数的关系。     

矩量法分析埋地三维目标的近场电磁散射

采用混合位积分方程（MPIE）和基于RWG基函数的矩量法分析计算了埋地三维目标的近场电磁散射问题,利用二级离散复镜像（DCIM）和广义函数束（GPOF）相结合的方法求解近场Sommerfeld积分,很好地解决了多层媒质中电磁散射计算中的棘手问题,其方法简练、精确、高效,数值分析结果与有关文献吻合很好,证实了该方法的正确性和通用性。此外,该文还通过计算比较了不同观察点、不同目标埋地深度及不同地层媒质参数的电磁散射特性。     

埋地三维复杂介质目标电磁散射特性分析

采用混合位积分方程（MPIE）和基于四面体元基函数的矩量法分析计算了埋地三维介质目标电磁散射问题,利用二级离散复镜像（DCIM）和广义函数束（GPOF）相结合的方法求解近场Sommerfeld积分,很好地解决了多层媒质中复杂目标电磁散射计算中的棘手问题,其方法简练、精确、高效,数值分析结果与有关文献吻合很好,证实了该方法的正确性和通用性。此外,该文还通过计算比较了不同观察点、不同目标埋地深度及介质参数的电磁散射特性。     

三维涡流计算中最少变量数边界积分方程的一个注记

本文回顾了求解三维电磁场涡流问题的数值计算方法,其中最少变量数边界积分方程法(Boundary Integral Equations of Minimum Order Method)具有很多优点.但提出该方法的论文以及后续论文中的边界积分方程中存在一些错误,本文给出了边界积分方程的极限推导过程,改正了这些错误.     

三维矢量散射积分方程中奇异性的分析

本文研究了电场积分方程（ＥＦＩＥ）中被积函数奇异性的处理方法,特别是三维矢量散射分析中出现的高阶奇异性,给出了两种解决积分方程奇异性的数值方法。一种方法是计算Ｏ（１／Ｒ）阶奇异积分转移法,另一种方法是为解决Ｏ（１／Ｒ＾２）高阶奇异积分的数值计算问题的,它是通过排除一包含奇点的有限小块,而这一小块区域对积分的贡献为零,从而使积分方程在整个积分域变得数值可积。     

基于GPU 的二维FDTD 并行计算

由于稳定性条件的要求和采用Yee 元胞体离散的方式求解Maxwell 方程,用FDTD 计算目标电磁散射时需要 消耗大量的计算资源,计算往往需要较长时间。采用并行技术是提高计算效率的有效途径,本文基于计算统一架构 CUDA 模型,给出了利用图形处理器（GPU）实现二维FDTD 并行计算的实现方法。给出了二维Mur 边界和PEC 边界 的数值算例,计算结果表明,采用GPU 计算大大的提高了计算效率。     

基于超级计算机的矩量法性能分析与优化

复杂目标的精确电磁特性分析往往需要巨大的存储和极长的计算时间。针对这一问题,结合国内发展迅速的超级计算机系统,研究了具有精确高效仿真能力的高性能电磁算法——高阶矩量法。提出了单元预选法来消除矩阵并行填充过程中的无效计算,加速矩阵填充过程。提出了一种具有更少的通信次数和通信量的新型并行LU分解算法,加速矩阵方程求解过程。数值测试表明提出的矩阵并行填充算法和矩阵方程并行求解算法在超级计算机平台上都能获得较高的并行性能,大幅提高了矩量法的仿真能力。     

金属-各向异性介质体组合目标频域体表积分方程矩量法

利用体表积分方程矩量法求解了具有任意的介电常数张量和磁导率张量的各向异性介质与金属的组合目标的电磁散射问题.给出了基于RWG面基函数和SWG体基函数的体表积分方程阻抗矩阵元素表达式并详细推导了阻抗矩阵元素所涉及的各种积分运算的计算方法;通过数值计算实例与解析解或其它数值方法的详细对比分析,证明了计算公式的正确性.     

基于时域混合场积分方程求解目标瞬态散射特性

当入射平面波的频谱包含目标的谐振频点时,时域电场积分方程和时域磁场积分方程求解的表面电流不稳定,会出现后期震荡现象。通过线性组合时域电场积分方程和时域磁场积分方程,可以获得一种混合场积分方程。数值结果显示,这种混合场积分方程消除了因内部谐振引起的后期震荡,得到了稳定的表面电流分布和远区散射场。     

ANALYSIS OF THE SCATTERING OF RIVET ON AIRCRAFT

This letter investigates the scattering characteristic of the rivets on aircraft.The electric Field Integral Equation (EFIE)is used with the moment to calculate the current distribution on the surface of the rivet.With the application of Gaussian integral corresponding triangular cell,the time to fill the Z matrix is greatly reduced.Finally,the RCS of a type of rivet on aircraft is analyzed.     

精确快速计算时域积分方程中奇异性积分的新方法

该文首先利用参数坐标和广义Duffy坐标变换将时域电场积分方程(TDEFIE)的奇异性积分转换成非奇异性积分,然后根据时间基函数的特点将该积分转换成可以快速精确计算的分区域积分。数值计算实例表明,该方法可以大幅度提高求解TDEFIE的后时稳定性和解的精度,而不必采用任何求平均的过程。该方法适用于任意类型的时间基函数并可方便地推广到高阶曲面拟合和高阶空间基函数情形。     

Calculation of CFIE impedance matrix elements with RWG and n/spl times/RWG functions

The method of moments (MoM) solution of combined field integral equation (CFIE) for electromagnetic scattering problems requires calculation of singular double surface integrals. When Galerkin's method with triangular vector basis functions, Rao-Wilton-Glisson functions, and the CFIE are applied to solve electromagnetic scattering by a dielectric object, both RWG and n/spl times/RWG functions (n is normal unit vector) should be considered as testing functions. Robust and accurate methods based on the singularity extraction technique are presented to evaluate the impedance matrix elements of the CFIE with these basis and test functions. In computing the impedance matrix elements, including the gradient of the Green's function, we can avoid the logarithmic singularity on the outer testing integral by modifying the integrand. In the developed method, all singularities are extracted and calculated in closed form and numerical integration is applied only for regular functions. In addition, we present compact iterative formulas for computing the extracted terms in closed form. By these formulas, we can extract any number of terms from the singular kernels of CFIE formulations with RWG and n/spl times/RWG functions.     

飞机舵面缝隙缺陷建模及电磁散射特性分析

为了研究飞机舵面缝隙在飞机头向威胁角域的散射特性,提取舵面前端缝隙设计了雷达散射截面(Radar Cross Section,RCS)数值仿真分析模型.采用混合场积分方程和多层快速多极子算法进行了RCS仿真计算,并以RCS峰值、波峰宽度、均值增量三个评价指标分析散射特点.舵面前端缝隙的垂直极化散射明显(不同频率下的均值...     

一种连接双层传输线Via结构的全波分析

推导了金属盒中介质平面上水平电偶极子和垂直电偶极子的格林函数,针对一种双层带状线或微带线的Via结构建立了相应的电场积分方程,用矩量法计算了无调配装置和有调配装置的Via的反射系数,并与其它方法作了比较。     

Comparison of Different Methods for Calculating Gyrotron Quasi-Optical Mode Converters

This paper presents the use of combination of three methods for calculation and synthesis of high-efficiency microwave mode converters, such as radiators of gyrotrons. The analytical method yields immediate estimates of mode converter dimensions, the Scalar Integral Equation (SIE) allows one to synthesize efficiently the optimal profile of the mode converter, and the most accurate Electric Field Integral Equation (EFIE) is used to check all transmission characteristics of the converter including calculations of reflection and cross-polarization. The combination of these three methods is an optimal for the mode converter design. Just so the launcher was designed for a quasi-optical mode converter used in the 60 GHz gyrotron in the TE7,3 operating mode. The simulation results agree well with the measured data. The paper also presents for the first time an accurate derivation of the SIE method.     

Combined field integral equation formulation for inhomogeneous two and three-dimensional bodies: the junction problem

A combined field integral equation (CFIE) formulation is presented for two- and three-dimensional bodies having discrete dielectric and conducting regions. A three-dimensional case is restricted to bodies of revolution (BORs). The two-dimensional case is analogous to the BOR case when the Fourier mode number is zero. The method of moments (MM) is used to solve the CFIE in terms of two integral operators. It is shown that the CFIE formulation yields accurate answers for scattering problems where the scatterer may be internally resonant. The CFIE results were validated using Mie series results and measured data. The junction problem associated with the CFIE-based formulation is explicated, and several geometries with multiple junctions are used to validate the general CFIE formulation. A number of configurations are tested where the penetrable region consisted of a free-space coating. Extensive numerical studies have shown that such limiting cases are sensitive indicators of the stability of MM solutions and allow direct comparison of different configurations     

Combined field integral equation formulations for electromagnetic scattering from convex geometries

The properties of different forms of the combined field integral equation (CFIE) formulation of electromagnetic scattering from convex, perfect electrically conducting geometries are considered. Several difficulties encountered in the numerical implementation of the traditional CFIEs of electromagnetic scattering theory are discussed. An alternate form of the CFIE is introduced which is free of many of the deficiencies of traditional formulations for smooth, convex geometries. The improved numerical properties of the new formulation are illustrated with numerical examples.