并行高阶矩量法分析大型阵列天线的辐射特性

随着计算机多核技术和计算机集群技术的发展,并行高阶矩量法可以解决复杂大型目标的电磁特性。文中首 先对单个天线单元在高阶矩量法与有限元方法下的结果进行对比,验证了本文方法的正确性和可行性,然后给出了一 个36×12 单元的伞形印刷振子天线阵列的方向图结果,从而说明了本文方法可以处理实际工程中的大规模挑战性问 题。     

并行高阶矩量法分析舰队RCS和其它电磁特性

随着计算机多核技术和计算机群技术的发展和MPI并行技术的应用,使得并行高阶矩量法可以解决复杂大型目标的电磁特性。文中介绍了并行高阶矩量法的基本理论：高阶基函数、并行矩阵填充和并行矩阵求解,并在这些理论的基础上应用其分析舰队的RCS和其它电磁特性来说明这种数值算法的可行性和快速性。     

偶极子天线矩量法分析

基于矩量法对细直天线的电流分布及输入阻抗进行了分析，并与理论计算进行比较，结果表明：矩量法在计算较细的半波振子天线时，有较好的计算结果，对粗振子的结果误差比较大。     

谐振式四臂螺旋天线的矩量法分析

本文对Nakano简化的曲线天线积分方程核做了更便于数值计算的处理;运用矩量法分析,计算了谐振式四臂螺旋天线的圆极化方向图、增益、轴比、前后比及赋形特性等,并研究了馈电方法和导电板对天线性能的影响。     

柱形等离子体天线辐射特性的矩量法分析

基于矩量法计算了当等离子体天线工作频率远小于等离子体频率时,密度均匀分布的柱形等离子体天线表面电流分布、辐射方向图、输入阻抗及天线效率等天线参数.计算结果表明:等离子体天线具有与金属铜天线类似的辐射特性,并且随等离子体参数变化而改变.此外既可以通过等离子体天线的动态重构,也可以在损失部分效率的前提下选取固定的等离子体参数,获得天线的宽带特性.     

核外分块求解方法计算电大平台天线辐射特性

载体平台对天线辐射特性的影响不容忽视,但由于计算机物理内存的限制,使得某些电大平台天线辐射问题无法计算.针对上述问题,采用了利用硬盘代替内存的核外求解方法;为加快求解速度,提出了一种核外分块高斯消元方法.将数据按块集中读写,从而极大地缩短了对硬盘操作的时间.分别计算了金属圆柱平台天线和车载平台天线的辐射方向图.结果表明,本方法可快速求解电大平台天线辐射问题,求解时间与核内方法只相差5.9%,而且不损失计算精度.     

国产CPU 平台中高阶矩量法10 万核并行性能

针对国产超级计算机平台上大规模电磁仿真软件相对匮乏,本文将并行高阶矩量法程序移植到国产超级计算机平台上,并以机载线天线阵列的辐射特性计算为例对其并行性能进行了测试和评估。实现了并行高阶矩量法单一任务突破10 万CPU 核规模,这是目前在国产超级计算机平台上实现的最大规模并行矩量法计算。以1440 核为基准,使用CPU 核数达到102400,并行规模扩大约70 倍时,并行矩量法矩阵方程求解并行效率仍在50%以上。这一研究工作,使利用纯国产超级计算机对复杂电大电磁系统进行精确高效仿真成为可能。     

Solution of large complex problems in computational electromagnetics using higher-order basis in MoM with out-of-core solvers

In a recent invited paper in the IEEE Antennas and Propagation Magazine, some of the challenging problems in computational electromagnetics were presented. One of the objectives of this note is to simply point out that challenging to one may be simple to another. This is demonstrated through an example cited in that article. The example chosen is a Vivaldi antenna array. What we discuss here also applies to the other examples presented in that article, but we have chosen the Vivaldi antenna array to help us make our point. It is shown in this short article that a higher-order basis using a surface integral equation a la a PMCHWT (Poggio-Miller-Chu-Harrington-Wu-Tsai) method-of-moments formulation may still be the best weapon that one have in today's arsenal to deal with challenging complex electromagnetic analysis problems. Here, we have used the commercially available code WIPL-D to carry out all the computations using laptop/desktop systems. The second objective of this paper is to present an out-of-core solver. The goal is to demonstrate that an out-of-core 32-bit-system-based solver can be as efficient as a 64-bit in-core solver. This is quite contrary to the popular belief that an out-of-core solver is generally much slower than an in-core solver. This can be significant, as the difference in the cost of a 32-bit system can be 1/30 of a 64-bit system of similar capabilities using current computer architectures. For the 32-bit system, we consider a Pentium 4 system, whereas for the 64-bit system, we consider an Itanium 2 system for comparison. The out-of-core solver can go beyond the 2 GB limitation for a 32-bit system and can be run on ordinary laptop/desktop; hence, we can simultaneously have a much lower hardware investment while better performance for a sophisticated and powerful electromagnetic solver. The system resources and the CPU times are also outlined.     

Solving large complex problems using a higher-order basis: parallel in-core and out-of-core integral-equation solvers

The future of computational electromagnetics is changing drastically with the new generation of computer chips, which are multi-cored instead of single-cored. Previously, advancements in chip technology meant an increase in clock speed, which was typically a benefit that computational code users could enjoy. This is no longer the case. In the new roadmaps for chip manufacturers, speed has been sacrificed for improved power consumption, and the direction is multi-core processors. The burden now falls on the software programmer to revamp existing codes and add new functionality to enable computational codes to run efficiently on this new generation of multi-core processors. In this paper, a new roadmap for computational code designers is provided, demonstrating how to navigate along with the chip designers through the multi-core advancements in chip design. A new parallel code, using the Method of Moments (MoM) and higher-order functions for expansion and testing, and executed on a range of computer platforms, will illustrate this roadmap. The advantage of a higher-order basis over a subdomain basis is a reduction in the number of unknowns. This means that with the same computer resources, a larger problem can be solved using higher-order basis than using a subdomain basis. The matrix filling for MoM with subdomain basis must be programmed with multiple loops over the edges of the patches to account for the interactions. However, higherorder basis functions, such as polynomials, can be calculated more efficiently with fewer integrations, at least for the senial code. In terms of parallel integral-equation solvers, the differences between these categories of basis functions must be understood and accommodated. If computational codes are not written properly for parallel operation, taking into account the central processing unit (CPU) architecture and operating system, the result will be an extremely inefficient code. The research presented here will show how to take th     

应用矩量法对任意线天线辐射特性的分析

采用矩量法对线形导体上的辐射特性进行了分析，该方法是基于伽略金法，以三角矢量函数作为空间的基函数和检验函数对任意形状的线结构的电场积分方程进行求解，并以此求解天线上的电流分布和天线的功率辐射方向图。给出了篇例，结果表明，该方法是有效的，为超宽带天线的分析奠定了基础。     

MoM快速全波分析微带天线阵

微带天线及其阵列有着十分广泛的应用,对它们的精确分析也越来越引起人们的重视.首先采用混合位积分方程的MoM在空域建立全波分析模型,然后采用离散复镜像求解空域格林函数,从而提高了计算效率.三角形网格剖分计算目标也使得本文方法更适合分析复杂结构.同时,又将自适应的有理逼近和MoM结合,用于分析微带天线的宽频带特性和单站RCS,计算效率进一步提高.几个典型实例的数值结果表明了本文方法的有效性.     

有限元法与UTD结合计算机载天线方向图

为了计算机载天线的方向图,近区矢量场可以作为有限元法(FEM)与UTD(一致性几何绕射理论)的结合点,将二者结合以解决类似的工程问题.首先利用基于有限元法的软件HFSS计算相控阵天线的近区矢量场,然后将此结果作为UTD方法的源进一步计算以预测该相控阵天线的受扰特性.结果表明这种方法可有效用于分析机载相控阵天线的辐射特性.     

金属多面体上低剖面天线的矩量法分析

采用矩量法对任意形状导体上的低剖面天线进行了整体分析,其中导体采用三角形面元矢量基函数、细线结构采用三角形基函数、线面连接处采用特殊的基函数,在处理积分奇异时,通过坐标变换、积分转化、降维处理实现了奇异积分的精确快速计算,以平板单极子天线为例,验证了该方法的有效性.最后,利用该方法对金属立方体上的低剖面电小环天线特性进行了分析,得出的结论对设计复杂载体上低剖面天线或天线阵有一定的参考价值。     

核外并行ACA算法计算电大目标RCS

矩量法计算电大目标雷达散射截面〖WTBZ〗（Radar Cross Section,RCS）将消耗巨大计算机资源. 采用自适应交叉近似算法（Adaptive Cross Approximation Algorithm,ACA）降低了计算量和存储量,同时结合核外求解技术,并对算法进行了并行化处理,从而进一步降低了大型计算对计算硬件的需求,提高了计算速度. 通过算例证明了该算法在不损失矩量法精度的前提下可大幅缩减计算时间和内存需求.     

机载天线隔离度仿真与分析

天线隔离度是机载电子系统实现电磁兼容预测的重要参数.根据反应积分原理,提出采用孤立天线远场方向图来替代实际环境中天线的办法,简化分析模型,在保证分析精度的基础上,提高计算效率,从而高效完成电大尺寸环境中天线隔离度的仿真分析.通过在自由空间情况下进行测试,验证了仿真结果的准确性.     

Analysis of microstrip filters using efficient MoM approach

An efficient approach for the analysis of microstrip filters is proposed. The computation is based on the method of moments (MoM) in which rooftop basis functions on non-uniform meshes, an analytical integration technique and numerical matched loads are combined. The resulting MoM matrix is then compressed and computation time is considerably reduced     

复杂环境中短波天线的MoM/FDTD混合法分析

利用电磁场数值计算方法中的矩量法/时域有限差分（MoM/FDTD）混合方法,分析了复杂环境中短波天线的电磁辐射性能,建立了短波双极天线的自由空间模型。采用矩量法和时域有限差分法相结合,对其模型进行仿真计算,并将计算结果和已有的文献进行比较,验证了混合方法计算结果的可行性、准确性。总结了该模型对短波天线远区场影响的有益经验,为改善短波天线性能提供了设计参考。