共查询到17条相似文献,搜索用时 170 毫秒
1.
2.
3.
由于通信天线经常工作在宽带或者多频带模式,为了对电磁干扰下的通信天线进行保护,对天线时域特性的仿真必不可少.其中一个需要研究的问题就是将天线装载于金属平台上并同时使用脉冲源激励.文中使用一种具有通用性的数值方法--时域电场积分方程,仿真了电磁脉冲照射下螺旋天线的宽带瞬态响应特性.采用拉革尔多项式作为全域时间基函数来展开时间变量,获得求解线天线散射辐射问题的时域电场积分方程,也就是阶数步进递推格式,最后使用数值计算得到了螺旋天线的瞬态响应特性. 相似文献
4.
时域电场、磁场和混合场积分方程已被广泛用来分析散射体的时域散射响应.基于适当的空间积分方法和隐式的时间步进算(MOT)法在求解时域磁场和混合场积分方程时总是稳定的,然而在求解TDEFIE时则是不稳定的.在本文中,时域电场积分方程的非奇异性积分采用标准的高斯求积法来计算;而利用参数坐标变换和极坐标变换将其奇异性积分转换成为可以分区域精确快速计算的非奇异性积分.通过数值实验表明,利用该方法可以非常精确稳定地求解时域电场积分方程,即使是在时间迭代后期也不必采用任何求平均的过程;另外,该方法可以用于任意时间基函数并可以推广到高阶空间基函数的情形. 相似文献
5.
6.
7.
8.
RWG(Rao-Wihon-Glisson)三角基函数为基础的矩量法是分析偶极子天线阵列的有效方法.通过求解阻抗矩阵和矩量方程,可分析天线互耦特性.偶极子模型法是将包含2个三角的RWG边元的表面电流分布用具有等效偶极子矩量的无穷小偶极子代替来求解天线辐射场.运用偶极子模型法替代传统的电场积分法来求解阵列方向图,对考虑互耦偶极子阵列的方向图进行了仿真,并对比分析了和理想情况下的差异.同通常的电场积分方程法相比,此方法具有计算简便,物理意义明确,可分析任意形状的天线等特点. 相似文献
9.
本文研究了一种可以高效求解任意非常规目标电磁散射的修正电场积分方程方法.借助磁场积分方程主值项的提取,加入到传统电场积分方程中,将传统的一次迭代求解过程转变成逐渐逼近真解的内外两层迭代.其外层迭代不断刷新电流,最终得到精确解.加入磁场主值项的修正电场积分方程显著降低了条件数,同时保留了原电场积分方程普适性强,可用于处理任意非常规目标的优点.对于每一外层迭代步中电流的求解,本文采用了加速矩阵矢量相乘的多层快速非均匀平面波算法,形成高效的内层迭代求解.数值结果表明,该方法在保证精度的同时,可以显著降低问题的求解时间. 相似文献
10.
11.
We investigate the accuracy of the combined-field integral equation (CFIE) discretized with the Rao-Wilton-Glisson (RWG) basis functions for the solution of scattering and radiation problems involving three-dimensional conducting objects. Such a low-order discretization with the RWG functions renders the two components of CFIE, i.e., the electric-field integral equation (EFIE) and the magnetic-field integral equation (MFIE), incompatible, mainly because of the excessive discretization error of MFIE. Solutions obtained with CFIE are contaminated with the MFIE inaccuracy, and CFIE is also incompatible with EFIE and MFIE. We show that, in an iterative solution, the minimization of the residual error for CFIE involves a breakpoint, where a further reduction of the residual error does not improve the solution in terms of compatibility with EFIE, which provides a more accurate reference solution. This breakpoint corresponds to the last useful iteration, where the accuracy of CFIE is saturated and a further reduction of the residual error is practically unnecessary. 相似文献
12.
Direct solution of the EFIE with half the computation 总被引:1,自引:0,他引:1
When using the electric field integral equation (EFIE) with the same basis and testing functions, a complex symmetric (non-Hermitian) moment method matrix results. Stable methods that directly solved this matrix with roughly half the storage and execution time required for the nonsymmetric case exist. Apparently these methods are relatively unknown among moment method practitioners. Furthermore, the resulting advantage in storage and execution time of the EFIE (when a direct solution is used) over other methods (such as the MFIE and CFIE) seems not to be widely appreciated 相似文献
13.
Contopanagos H. Dembart B. Epton M. Ottusch J.J. Rokhlin V. Visher J.L. Wandzura S.M. 《Antennas and Propagation, IEEE Transactions on》2002,50(12):1824-1830
We introduce a new version of the combined field integral equation (CFIE) for the solution of electromagnetic scattering problems in three dimensions. Unlike the conventional CFIE, the new CFIE is well-conditioned, meaning that it is a second kind integral equation that does not suffer from spurious resonances and does not become ill conditioned for fine discretizations (the so-called "low-frequency problem"). The new CFIE combines the standard magnetic field integral operator with an analytically preconditioned electric field integral operator. We also report numerical results showing that the new formulation stabilizes the number of iterations needed to solve the CFIE on closed surfaces. This is in contrast to the conventional CFIE, where the number of iterations grows as the discretization is refined. 相似文献
14.
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. 相似文献
15.
A general method for deriving higher order impedance boundary conditions is described. It is based on solving an appropriate canonical problem exactly in the spectral domain. After approximating the spectral impedance terms as a ratio of polynomials in the transform variable, elementary properties of the Fourier transform are used to obtain the corresponding boundary condition in the spatial domain. The method is applicable to multilayer coatings with arbitrary constitutive relations. Higher-order boundary conditions which neglect the effects of curvature are derived for a dielectric coating using the method. The boundary condition equation and the magnetic field integral equation are solved simultaneously using the method of moments, yielding the bistatic and monostatic radar cross section for dielectric-coated superquadric cylinders. The method is also applicable to a combined field integral equation (CFIE) solution, which can be used to eliminate the internal resonance problem associated with either the electric field integral equation (EFIE) or magnetic field integral equation (MFIE) 相似文献
16.
Petre P. Swaminathan M. Veszely G. Sarkar T.K. 《Antennas and Propagation, IEEE Transactions on》1993,41(8):1069-1080
A set of integral equations based on the surface/surface formulation are developed for analyzing electromagnetic scattering by one-dimensional periodic structures. To compare the accuracy, efficiency, and robustness of the formulation, the electric field integral equation (EFIE), magnetic field integral equation (MFIE), and combined field integral equation (CFIE) are developed for analyzing the same structure for different excitations. Due to the periodicity of the structure, the integral equations are formulated in the spectral domain using the Fourier transform of the integrodifferential operators. The generalized-biconjugate-gradient-fast Fourier transform method with subdomain basis functions is used to solve the matrix equation 相似文献