共查询到19条相似文献,搜索用时 187 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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基于一种改进的Z变换-时域有限差分(Z-Finite-Difference Time-Domain,Z-FDTD)方法,即将双各向异性色散介质的频域本构方程先转化到Z域中,再利用Z变换的性质将其转换到时域,得到离散时域的FDTD迭代式,分析了双各向异性色散介质电磁波传播特性.由于Omega媒质是一种典型的双各向异性色散介质,以此为例编程计算了垂直入射在Omega介质板情形下产生的同极化和交叉极化电磁波的反射和透射情况,并通过算例和解析解对比验证了算法的正确性,最后对其电磁散射特性进行了分析. 相似文献
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FEM/BEM混合法计算各向异性不均匀介质柱电磁散射 总被引:1,自引:0,他引:1
应用有限元-边界元(FEM/BEM)混合法计算二维各向异性不均匀介质柱电磁散射,对介质柱内、外区域分别采用有限元和边界元法进行分析,然后应用边界条件建立部分稀疏部分满填充的矩阵方程.应用内观法结合多波前法求解该矩阵方程,分别计算了均匀分布和不均匀分布的各向异性介质柱的雷达散射截面.数值计算表明,有限元-边界元混合法在分析和计算不均匀开放域电磁问题时有一定的优势. 相似文献
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基于一种改进的Z变换-时域有限差分(Z-Finite-Difference Time-Domain, Z-FDTD)方法, 即将双各向异性色散介质的频域本构方程先转化到Z域中, 再利用Z变换的性质将其转换到时域, 得到离散时域的FDTD迭代式, 分析了双各向异性色散介质电磁波传播特性.由于Omega媒质是一种典型的双各向异性色散介质, 以此为例编程计算了垂直入射在Omega介质板情形下产生的同极化和交叉极化电磁波的反射和透射情况, 并通过算例和解析解对比验证了算法的正确性, 最后对其电磁散射特性进行了分析.
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本文推导了二维横各向异性媒质中电磁散射的差分方程,得到了9点的差分格式,并将不变性测试方程与该差分方程结合计算了具有任意横截面,非均匀,有耗和一般张量形式的二维向异性媒质柱的电磁散射,文中给出了一些典型数值算例,数值结果表明,该方法在分析计算此类问题时是有效的且具有一定的优势。 相似文献
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Paul J. Christopoulos C. Thomas D.W.P. 《Antennas and Propagation, IEEE Transactions on》1999,47(10):1535-1542
For pt. I see ibid., vol.47, no.10, p.1528-34 (1999). Transmission-line modeling (TLM) can be used for the time-domain simulation of electromagnetic wave propagation in anisotropic and bi-anisotropic media. In this paper, Z-transform methods are utilized to obtain the time-domain iteration procedures for propagation in anisotropic and bi-isotropic materials. For clarity, the method is first developed for one-dimensional (1-D) propagation and then extended to the three-dimensional (3-D) case 相似文献
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Hao-Hui Chen 《Microwave Theory and Techniques》2003,51(3):848-855
A full-wave analysis incorporating the finite-element method (FEM) and the method of lines (MoL) is presented in this paper to investigate a planar or quasi-planar transmission-line structure containing complex geometric/material features. For a transmission-line structure being considered, the regions containing complex media are modeled by the FEM while those consisting of simple media with simple geometry are analyzed using the MoL. From the field solutions calculated by MoL, the boundary conditions are constructed. The boundary integrals involved in finite-element analysis are then carried out using these boundary conditions. Since the finite-element analysis is employed only in the complex parts of the structures, while other parts are handled by the MoL, this approach not only retains the major advantage of the FEM in simulating complex structures but also becomes more efficient than the conventional finite-element analysis. Good agreement between the calculated results and those reported in the available literature is obtained and thus validates the present approach. Furthermore, proficient computational efficiency of this method is demonstrated by examining its convergence property. Finally, a number of relevant transmission-line structures are analyzed to illustrate the applications of this approach. 相似文献
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In this paper, an efficient finite-clement formulation is presented for the analysis of the propagation characteristics in arbitrarily shaped lossy inhomogeneous waveguides loaded with chiral media. It is a simplified form of the one proposed for the bi-anisotropic media. In this formulation, showing no spurious modes, the frequency or the propagation constants may be treated as eigenvalues of a resulting sparse quadratic eigenproblem. However, in order to handle losses easily and to facilitate computation of complex modes, the frequency is specified as an input parameter and the eigensystem is solved for the complex propagation constant as the eigenvalue. This sparse eigensystem is further transformed into a generalized one, thus maintaining the sparse properties of the matrices. New numerical finite-element results are presented 相似文献
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An efficient and systematic procedure is described for the finite-element solution of a class of electromagnetic radiation and scattering problems involving unbounded geometries. The numerical procedure is well suited for analyzing infinite metallic structures with cavity regions filled with inhomogeneous and anisotropic media. The formulation is based upon an approach that combines the finite-element method (FEM) with the surface integral equation to truncate the mesh region. The efficiency of the proposed technique arises from the use of the Green's function of the first kind in the surface integral. Illustrative numerical representations that demonstrate the validity, versatility, and efficiency of the method are included 相似文献
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In this paper single and coupled equivalent transmission lines are developed for the propagation of modes in reciprocal and nonreciprocal, anisotropic, bi-isotropic, and bi-anisotropic waveguides. The transmission lines are described by the generalized telegrapher's equations. In order to develop these transmission line models some properties related to reciprocity, bi-directionality, and mirroring, of general waveguides and generalized transmission lines are investigated. The transmission line models are based on the reciprocity theorem and are valid for arbitrary frequencies 相似文献
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While physical restrictions on the constitutive parameters of linear bi-anisotropic media are well known, attention has been meager on the issue of mathematical consistency, when specializing the Maxwell equations for material media. The authors show that such a consistency requirement results in a mathematical constraint: an algebraic relation between the constitutive parameters. Repercussions for specific types of linear media are discussed, most importantly, the consequence that bi-isotropic media must be reciprocal 相似文献
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AKHLESH LAKHTAKIA 《International Journal of Electronics》2013,100(6):1355-1362
A self-consistent derivation is given for the Maxwell-Garnett model for a very general particulate composite. The bi-anisotropic inclusions are supposed to be randomly embedded in a bi-isotropic host medium. It is seen that the effective medium is also bi-anisotropic in general. 相似文献
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Finite-Element Formulation in Terms of the Electric-Field Vector for Electromagnetic Waveguide Problems 总被引:1,自引:0,他引:1
《Microwave Theory and Techniques》1985,33(10):900-905
A vector finite-element method for the analysis of anisotropic waveguides with off-diagonal elements in the permeability tensor is formulated in terms of all three components of the electric field. In this approach, spurious, nonphysical solutions do not appear anywhere above the "air-line." The application of this finite-element method to waveguides with an abrupt discontinuity in the permittivity is discussed. In particular, we discuss how to use the boundary conditions of the electic field at the interface between two media with different permittivities. To show the validity and usefulness of this formulation, examples are computed for dielectric-loaded waveguides and ferrite-loaded waveguides. 相似文献
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An efficient algorithm for rigorously deriving the spectral-domain impedance dyadic Green's function for MMICs on general complex anisotropic or bi-anisotropic substrates is developed. Its main advantage is that it provides closed-form expressions for transverse propagation constants and related immittances in the spectral domain and, therefore, allows the following parameters to be taken into account: dielectric and magnetic losses of anisotropic or bi-anisotropic media without restrictions to the magnitude of tensor elements, alternative directions for magnetic bias, and the finite metallization thickness of conventional conductors and/or superconductors including their losses. Microstrip and coplanar waveguide structures in open, shielded, and conductor-backed technology can be treated. The theory is verified by comparison with previously published data, and its flexibility is demonstrated for both superconductor and conventional conductor (M)MIC structures 相似文献