共查询到20条相似文献,搜索用时 15 毫秒
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本文利用矢量波函数变换方法讨论了两媒质半空间的电磁散射问题,从Maxwell方程出发,讨论了单矩法在三维复杂形体散射问题上的实施。并在数学球面上将内部区域的有限元解与外部区域矢量波函数变换的结果相匹配,从而得到复杂埋入体的电磁散射特性。作为检验和示例,本文计算了在平面波照射下自由空间导体球,埋入导体球,埋入介质覆盖钝锥等的散射场,其中一些结果与可供比较的经典解或其它算法的结果进行了比较,吻合较好。 相似文献
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虽然快速多极子算法FMM(Fast Multipole Method)和多层快速多极子算法MLFMA(Multi-Level Fast Multipole Algorithm)是解决复杂目标电磁散射问题比较有效的方法,但是当问题的规模较大时,传统的串行FMM 和MLFMA难以胜任.本文在工作站网络系统NOW(Network Of Workstation)上采用并行处理技术来解决电大尺寸复杂目标电磁散射问题.结果表明:本文提出的并行解决方案与国内外相关成果相比不仅更具实用性,并行效率达到54%以上,且解决了串行方法难以解决的电磁散射问题,本文在四台DEC工作站构成的NOW系统上用32小时完成了未知量为160,000的雷达散射截面的计算. 相似文献
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A Novel Method to Analyze Electromagnetic Scattering of Complex Objects 总被引:19,自引:0,他引:19
The finite-difference time-domain (FD-TD) method is proposed as a means of accurately computing electromagnetic scattering by arbitrary-shaped extremely complex metal or dielectric objects excited by an external plane wave. In the proposed method, one first uses the FD-TD method to compute the near total fields within a rectangular volume which fully encloses the object. Then, an electromagnetic-field equivalence principle is invoked at a virtual surface of this rectangular volume to transform the tangential near scattered fields to the far field. To verify the feasibility of this method, the surface currents, near scattered fields, far scattered fields, and radar cross section of two canonical two-dimensional objects are presented. For these cases, it is shown that the FD-TD method provides magnitude of current and field predictions which are within ± 2.5 percent and further phase values within ± 30 of values predicted by the method of moments ( MOM) at virtually every point including in shadow regions. 相似文献
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本文分析表面不规则物体电磁波的散射特性,采用程函近似计算了散射强度角分布,结果提示,表面不平度和散射程度局部最大值及后向散射增强效应密切相关。 相似文献
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Electromagnetic Scattering From Objects Above a Rough Surface Using the Method of Moments With Half-Space Green's Function 总被引:1,自引:0,他引:1
Bo Guan Jian Feng Zhang Xiao Yang Zhou Tie Jun Cui 《Geoscience and Remote Sensing, IEEE Transactions on》2009,47(10):3399-3405
An efficient approach is proposed to analyze the electromagnetic scattering from objects above a 2-D perfectly electric conducting rough surface. A half-space Green's function with the rough-surface interface is first derived from the Kirchhoff approximation (KA). The method of moments is then applied to analyze the scattering problem of 3-D arbitrarily shaped objects above the rough surface. Since only the objects need to be discretized, the computational time and memory requirement are greatly reduced. The radar cross sections of typical objects above the rough surface have been computed using the proposed method. Numerical results show that the proposed method has good accuracy in the valid range of KA. 相似文献
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使用基于表面积分方程的矩量法来分析介质与理想导体混合体的电磁散射是计算电磁学的一大热点。对理想导体目标体表面建立电场积分方程,在介质目标体表面建立PMCHW方程组,与基于矩阵分块技术的自适应修正特征基函数法结合,对介质涂敷理想导体目标体的电磁散射进行分析,将其称之为EFIE-PMCHW-AMCBFM(E-P-AMCBFM)。并讨论不同参数如基函数阶数,矩阵块间重叠区域等对计算效率的影响,数值结果表明E-P-AMCBFM对于处理介质-理想导体混合体的电磁散射问题具有较高的精度和效率。 相似文献
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Zhang Y. H. Xiao B. X. Zhu G. Q. 《Geoscience and Remote Sensing, IEEE Transactions on》2006,44(12):3540-3546
Fast algorithms for electrically large objects buried in layered media are mainly hindered by two time-consuming processes. One is the table filling of Green's function, and the other is the solving of the impedance matrix equation. For the first, to accelerate the evaluation of the time-consuming Sommerfeld integral in the dyadic Green's function (DGF), the discrete complex image method (DCIM) is introduced to get a closed-form DGF. To further accelerate the calculation of DGF for the volume electric field integral equation (EFIE), DGF is split before applying DCIM. For the second, the iterative solver stabilized biconjugate gradient fast Fourier transform (BCGS-FFT) is combined with DCIM for solving the matrix equations. Meanwhile, the closed-form DGF enables the "spherical-mean" Green's function, which eliminates the singularity of Green's function. Numerical results show that the weaker singularity results in a faster and steadier convergence rate for iterative solvers 相似文献
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Wallen H. Jarvenpaa S. Yla-Oijala P. Sarvas J. 《Antennas and Propagation, IEEE Transactions on》2007,55(5):1423-1430
The multilevel fast multipole algorithm (MLFMA) is very efficient for solving large-scale electromagnetic scattering problems. However, at low frequencies, or when the discretization is small compared with the wavelength, both the MLFMA and the underlying integral equation formulation typically suffer from a subwavelength breakdown. For the electromagnetic scattering from a homogeneous dielectric object, we obtain a stable and well-conditioned surface integral formulation using a variant of the classical Muumlller formulation and linear basis functions. To overcome the subwavelength breakdown of the MLFMA, we use both propagating and evanescent plane waves to represent the fields. The implementation is based on a combination of the spectral representation of the Green's function and Rokhlin's translation formula. We also present a new interpolation scheme for the evanescent part, which significantly improves the error-controllability of the MLFMA-implementation. Several numerical results verify both the error-controllability and scalability of the proposed algorithm 相似文献
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应用空域分解法分析复杂目标的散射特性 总被引:2,自引:2,他引:0
本文讨论了几种散射体的空域分法的迭代形式。考虑到散射体的某一子域和几个了域产生的散射场有解析表达式或较高精度的近似解,给出三种迭代方式,以进一步减少存贮量和计算量。 相似文献
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Braaten B.D. Nelson R.M. Mohammed M.A. 《Antennas and Propagation, IEEE Transactions on》2008,56(1):142-150
Numerically stable electric field integral equations (EFIE) are presented for electromagnetic scattering problems that may include both electrically small geometrically complex and electrically large regions. A reduced integrand is achieved by implementing quasi-static assumptions in the electrically small regions, full-wave methods in the electrically large regions, and applying appropriate coupling relations between the regions. Use of the method provides computational efficiency as well as insight into the conditions under which the electromagnetic fields within electrically small regions of the problem can be assumed to be primarily capacitive or inductive in nature. The theoretical development of the method is highlighted in this communication and then applied to examples of electrically small, inductively-loaded, and capacitively-loaded monopole antennas. The accuracy of the results is verified with two independent methods. 相似文献
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本文研究了植被环境中相邻两目标的电磁散射问题.在互易原理的基础上,得到了计入相邻目标二次散射的散射场的积分表达式.推导得出了相邻有限长导体圆柱的二次散射场的闭式解,分析计算了其前向散射特性,并与矩量法的数值结果进行了比较. 相似文献