边界积分法及连接算法分析任意腔体的散射

本文利用边界积分法分析二维任意腔体的散射,给出一种基于微波网络原理的连接算法,将腔体分为几段,分别用积分方程法计算每段的广义导纳矩阵,然后利用连接算法将各段连接,得到整个腔体的口径导纳矩阵,最后由广义网络原理求解腔体的等效磁流及后向散射场。本文方法可作为一种机辅设计算法。     

任意形状天线罩的快速分析

将自适应积分算法与体积分方程相结合分析任意形状天线罩对天线辐射特性的影响。将任意形状的天线罩剖分成四面体，基于体积分方程的自适应积分快速算法求出天线罩上的感应电流，即可求出天线-天线罩系统的总场。自适应积分快速算法的应用提高了矩量法的计算速度，并大大缩减了需要的存储量，从而使该方法可用于分析电尺寸较大的天线罩.最后,分别计算了球形、锥形天线罩存在时理想电振子阵列的辐射方向图。     

导电平板上任意孔缝的TM波散射及传输特性分析

该文利用边界积分法分析导电平板上任意孔缝的TM波散射及传输特性,并引入了一种基于微波网络原理的连接算法以缓解计算机内存对所计算孔缝尺寸的限制。首先将孔缝内腔分为几段,用积分方程法分别计算每段的广义导纳矩阵,然后利用连接算法将各段连接起来得到整个孔缝的口径导纳矩阵,最后由广义网络原理求解孔缝的等效磁流、后向散射场以及传输系数。     

波导缝隙天线耦合特性的研究

本文研究了波导宽边上有一定厚度的任意两个纵向缝隙的耦合特性。采用矩量法将积分方程化为矩阵方程,对其中的内积进行合理的处理,求解了积分方程和相应的参数。根据计算和实验结果讨论了缝隙的内部和外部互耦对缝隙的口径场分布、导纳特性、谐振电导及谐振长度等特性的影响。     

大型波导缝隙阵与天线罩的一体化高效精确分析

针对带罩大型波导缝隙阵的辐射特性分析, 基于并行区域分解合元极算法, 提出一种多区域的精确高效算法.将每根波导缝隙天线以及天线罩实体目标作为一个有限元计算区域, 各区域之间通过基于各区域表面的边界积分方程进行耦合, 并于天线罩内部应用区域分解技术来降低计算资源实现高效计算.与传统单区域合元极的数值结果比较验证了该多区域方法的精确高效性, 还计算分析了带罩大型波导缝隙阵的频域辐射特性.     

导电平面上三维任意腔体的散射分析

本文利用边界积分法及连接算法分析导电平面上的三维腔体散射。在引入广义导纳矩阵后,可将腔体分为几段,分别用积分方程法计算每段的广义导纳矩阵。然后利用连接算法得到整个腔体的口径导纳矩阵。最后由广义网络原理求解腔体的口径等效磁流及后向散射场。本文方法极大地缓解了计算机内存对腔体尺寸的限制,提高了分析效率,可作为一种机辅设计算法。     

高速电路电源/地层间阻抗参数计算与分析

为了快速准确地计算高速电路地层与电源层之间的阻抗参数,基于边界积分方程提出了有效的计算方法.该方法充分利用了实际电源层/地层的结构特征,将三维电磁场问题转化为二维问题,减少了计算时间.由于在计算中不需要考虑整个 电源层/地层结构的格林函数,故该方法可以用于任意边界形状的电路板.基于提出的积分方程法,分析了介质相对电介质...     

时域积分方程MOT算法的推迟位时间卷积数值积分新方法

通过变量代换平滑三角形上推迟位（标量位函数和矢量位函数）并消除推迟矢量位旋度的奇异性,使得采用数值积分法就能够精确快速地计算任意正则时间基函数与推迟位函数及推迟矢量位旋度之间的时间卷积运算,可用于基于任意类型时间基函数的时域电场、时域磁场及其混合场积分方程时间步进（MOT ）算法。与时间卷积运算的解析法对比分析表明,该时间卷积数值积分方法能够精确快速地计算基于任意类型时间基函数和不同时间步长条件下时域积分方程MOT算法的阻抗矩阵元素;而具体的计算实例也表明,阻抗矩阵的精确计算显著地提升了时域积分方程MOT算法的后时稳定性和求解精度。     

波束波导电磁传输问题的积分方程数值解

应用积分方程数值方法建立了任意形状波束波导中电磁传输问题的物理模型;在馈电端用模式匹配方法分析端口匹配状况,基于等效原理建立波导的场激励模型,应用边界积分方程匹配波导的理想电导体（PEC）边界条件,最后,通过矩量法（MoM）和多层快速多级子算法（MLFMA）等数值算法给出了波束波导电磁传输和口面辐射的场解。数值实例证明了上述分析方法对于电大尺寸波束波导电磁传输问题的有效性和精确性。     

MOM/Lanczos-AWE算法快速求解良导体柱的RCS宽带与宽角响应

考虑导体柱的电磁散射 ,由于一般实际导体为良导体 ,若利用表面阻抗的边界条件 ,则良导体柱的电场积分方程 (EFIE)为第二类Fredholm积分方程 ;将矩量法 (MOM )应用到该积分方程时 ,该积分方程转化为第二类Fredholm矩阵方程。本文提出了一种求解第二类Fredholm矩阵方程的Lanczos AWE递归迭代快速算法 ,首先采用Lanczos技术快速求解在某一给定频率或角度时第二类Fredholm矩阵方程 ,得到在该频率或角度时良导体的表面电流分布 ;然后采用渐近波形估计 (AWE)技术求取所考虑的频段内任意频率或角度范围内任意角度时良导体的表面电流分布。根据表面电流分布预测了任意形状良导体柱的单站雷达散射截面 (RCS)的宽带与宽角响应。计算结果表明Lanczos AWE技术可大大加快MOM法的计算速度。     

广义网络法分析复杂孔缝耦合问题

本文利用广义网络法结合连接算法分析复杂孔缝耦合问题.首先根据孔缝的结构及填充特点将其内腔体分为适当的几段,利用边界元法分别计算每段的广义导纳矩阵,再借助连接算法将各段连接起来得到整个孔缝的口径导纳矩阵,最后由广义网络法求解孔缝的口径磁流、散射及传输场.该方法不仅在计算效率方面取得了较大突破,也使复杂填充孔缝的分析得到很大简化.     

Electromagnetic scattering from three-dimensional cavities via aconnection scheme

The electromagnetic scattering from arbitrary three-dimensional cavities is presented. To alleviate computational constraints for three-dimensional problems, a connection scheme is developed based on microwave network theory. This scheme allows the cavity to be divided into sections and each section to be analyzed independently of the rest of the cavity. Each section of the cavity is represented by a generalized admittance matrix which if formulated via a boundary-integral equation approach. Using the concept of input and load admittance, the aperture admittance matrix of the cavity can be derived by cascading the admittance matrices of individual sections. Once the cavity aperture admittance matrix is obtained, the aperture electric field and the backscattered field are found by the standard generalized network formulation. Numerical results are compared against modal solutions of regularly shaped cavities with good agreement. This connection scheme leads to a reduction in computational resources, especially for cavities with one dimension much larger than the other two     

Scattering from a cavity-backed slit in a ground plant-TE case

Two-dimensional transverse electric wave scattering from a cavity-backed slit in a ground plane is analyzed by R.F. Harrington and J.R. Mautz's (1976) generalized network formulation. The admittance matrix of the cavity or arbitrary shape and medium is obtained by the finite-element method. A variational equation for the cavity problem is established and then discretized to a matrix equation. An efficient algorithm using the modified frontal-solution algorithm is developed to solve the matrix equation. The solution is manipulated to get the admittance matrix of the cavity. The computed admittance matrix is added to the radiation admittance matrix of the equivalent magnetic current on a ground plane and is used to solve for the equivalent magnetic current on the slit. Numerical results for trapezoidal and coated rectangular cavities are included     

Electromagnetic transmission through inhomogeneously filled slotsin a thick conducting plane-arbitrary incidence

The penetration of an arbitrarily incident electromagnetic wave through a slot filled with inhomogeneous material in a thick conducting plane is analyzed. The solution is obtained via a combined finite-element method/method of moments algorithm based on the generalized network formulation. The discretization of the generalized network formulation is performed via the method of moments. The finite-element method is then used to compute the fields within the inhomogeneous interior cavity region, leading to the construction of the interior aperture admittance matrix. It is shown that with the use of entire domain basis functions, the construction of the aperture admittance matrices is computationally efficient. Furthermore, this method is attractive since it preserves the sparsity of the finite-element method matrix, reducing computational memory requirements. Some examples of the penetration of inhomogeneously filled slots of various cross sections are presented     

Scattering from a cavity-backed slit in a ground plane-TM case

Two-dimensional transverse-magnetic wave scattering from a cavity-backed slit in a ground plane is analyzed by the Harrington-Mautz generalized network formulation (1976). The admittance matrix of the cavity of arbitrary shape and medium is obtained by the finite-element method. The computed admittance matrix, added to the radiation admittance matrix of the equivalent magnetic current on a ground plane, is used to find a solution for the equivalent magnetic current on the slit. Numerical results for coated staggered cavities are included. Accurate results for the magnetic surface currents and radiation patterns have been obtained     

Electromagnetic scattering from and transmission through arbitraryapertures in conducting bodies

The general 3-D aperture coupling problem is formulated in terms of an integral equation for the equivalent magnetic current in the aperture, which is numerically solved by the method of moments. The aperture is characterized by two aperture admittance matrices, one for the exterior region and the other for the interior region. These two admittance matrices are determined separately but in a similar manner if the pseudo-image method is used. Numerically workable expressions are developed for the two aperture admittance matrices by decomposing each of them into a half-space admittance matrix and a supplementary admittance matrix. The half-space admittance is relatively easy to compute and has been investigated in the literature. The supplementary admittance matrix is expressed in terms of the generalized impedance combining the existing numerical codes for an arbitrarily shaped scatterer and for an arbitrary aperture in a conducting plane, one can obtain a code which is especially designed for an arbitrary aperture in a conducting surface of arbitrary shape     

Electromagnetic diffraction from a dielectric-filled slit-cylinderenclosing a cylinder of arbitrary cross section: TM case

A simple moment solution to the problem of the diffraction of a TM plane wave from an infinite, perfectly conducting slotted cylinder of an arbitrary cross section is summarized. The slit cylinder encloses a smaller perfectly conducting cylinder of an arbitrary cross section, and the space between the cylinders is filled with a dielectric material. The equivalence principle is used to obtain a set of coupled integral equations for the induced/equivalent surface currents on the cylinders, and the method of moments is used to solve numerically the integral equations. The electric field integral equation formulation is used. The advantages and the limitations of the method are discussed. Sample results for the induced current, aperture field, internal field, and scattering cross sections are given. These are in good agreement with some of the available published data