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UPML媒质中无条件稳定的二维ADI-FDTD方法 总被引:2,自引:0,他引:2
对单轴各向异性PML(UPML)媒质中二维TM波的交变方向隐式时域有限差分方向(ADI-FDTD),通过计算实例表明,ADI-FDTD方法在UMPL媒质中是无条件稳定的,其时间步长不受CFL稳定性条件的限制,并且当计算区域内具有精细差分网格时,其计算效率明显优于传统的时域有限差分方向(FDTD)。 相似文献
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在有外加恒定磁场条件下,等离子体为各向异性媒质。本文对电磁波在充有这种媒质的圆柱波导中传播的一种特殊模式即两个特征植相等条件遥波的传播特性进行了分析。给出了这种波的色用方程进行了计算讨论。 相似文献
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单轴双各向异性媒质柱体的电磁散射 总被引:3,自引:2,他引:1
采用广义多极子技术(Generalized Multipole Technique,GMT)分析了单轴双各向异性媒质任意截面柱体的电磁散射,计算结果与解析解和矩量法(Method of Moments,MoM)所得结果一致,讨论了该方法在电磁散射应用中的优缺点。 相似文献
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电磁波在包含各向异性媒质多层介质中传播的分析 总被引:1,自引:0,他引:1
对电磁波在包含各向异性媒质多层介质中的传播进行分析,给出了闭合形式的解,该结构可用作法拉第旋转器,与其它准光元件组合构成的准光环行器或隔离器。也可用作辐射口径,通过改变磁化场方向和强度实现波束扫描或极化变化,给出了法拉第旋转角计算结果和实验结果。 相似文献
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磁偶极在各向异性媒质中辐射的能流密度 总被引:1,自引:1,他引:0
对各向异性媒质中辐射问题的研究,求出磁偶极在各向异性媒质中辐射的具有张量形式的能流密度的普遍公式,在直角坐标系中,通过并矢计算,得出磁偶极在各向异性媒质中辐射的平均能流密度,并对磁偶极在各向异性媒质中的辐射作出了主要集中方向的判断,为研究各向异性媒质的开发应用提供了一个理论依据.对导出的新公式进行了验证. 相似文献
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超高频侧面波在森林中的损耗(英文) 总被引:5,自引:0,他引:5
本文考察了超高频(200~2000MHz)电磁波在森林中的传播问题。其中,发射偶极子和接收偶极子都在森林之中。在超高频段,树干、树枝、树叶的散射起着重要作用。这时,森林应被看成是离散的、随机的、各向异性的媒质,而在其中传播的无线电波应为平均场分量与起伏分量之和。就平均场分量而言,森林模型可以表示成四层媒质,其中用介于空间与大地间的两层各向异性媒质代表树干和树叶,以便计算其中的直接波、反射波和侧面波。计算表明,在超高频段,侧面波仍是主波。理论计算与现有实验数据有着良好的吻合。 相似文献
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用MEI方法计算电大尺寸非均匀各向异性涂覆媒质导体柱 总被引:1,自引:0,他引:1
本文运用有限差分技术,构造出非均匀各向异性媒质曲边网格的五点差分方程,借助不变性测试方程(MEI)这一新概念,成功地计算了电大尺寸任意厚度涂覆媒质的导体柱的RCS特性。在截断边界上采用MEI方程,使得截断边界十分接近散射体表面,从而使计算占用计算机的内存大大减少,同时与矩量法相比,还显著缩短了计算时间。本文在微机上计算的电大尺寸柱体周长达120个小长,是一般方法无法比所的。 相似文献
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磁偶极子激励的脉冲电磁波在损耗介质中的传播 总被引:1,自引:0,他引:1
本文用技坐标系中的时域有限差分法(FD-TD)模拟了磁偶极子激励的脉冲电磁波在均匀和轴对称分层均匀损耗介质中的传播问题,所得结果与文献中对类似问题的研究结果一致,从而相互得到了验证。并进一步证明Maxwell方程完全适应于脉冲电磁波在损耗介质中的传播问题。所用方法可用于电磁脉冲测并问题的进一步研究。 相似文献
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Danicki E. Langli B. Blotekjaer K. 《Antennas and Propagation, IEEE Transactions on》1995,43(1):97-104
A new method is proposed for analyzing electromagnetic (EM) wave scattering and waveguiding by a planar periodic system of thin and perfectly conducting strips. The method exploits some known properties of Fourier series with coefficients expressed by Legendre polynomials. The method can be used to solve problems associated with EM wave propagation and polarization having an arbitrary angle with respect to strips in arbitrary anisotropic media, multiperiodic systems of strips, and layered systems of skewed periodic strips. In the paper the method is presented by an example, namely the scattering of EM waves from a grating consisting of perfectly conducting strips in vacuum. Numerical calculations show that the method converges much faster than do alternative methods 相似文献
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采用基于地形学网格划分的时域FDTD 方法来研究地震期间(震前和震期)的极低频电磁现象。由于计算能力
的限制,这里主要关注的频率是50-250Hz。为了精确的仿真地震电磁环境,研究过程中引入了地形学信息和天然电磁噪
声(闪电)。在仿真中,通过对震区地震电磁激发,我们设置了多个不同的观测点来观测电磁波的传播并进行比较。同时,
电离层异常现象也被考虑在仿真过程中。我们的仿真结果证明了在震期电磁波存在传播异常现象,这也证明了之前研究
人员所观测到的数据的正确性。最后,我们总结了地震期间的电磁传播异常现象的初步规律。 相似文献
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本文用时域有限差分(FD-TD)法研究了建筑物内电磁波传播的计算问题.首先把计算结果与联合有限元法和边界元法的结果进行了对比,而后计算了不同频率电磁波从不同方向入射时建筑物内电磁场分布的特点.并计算了线源辐射的电磁波在建筑物内的传播及向外辐射的特性以及脉冲电磁波在建筑物内传播和反射的特点. 相似文献
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A finite-difference method for coding the third-order simplified one-way wave equation is analyzed and assessed for application to two-dimensional waveguide structures. The general formulation for the simplified one-way wave equations based on the expansion of the eigenvalue equation is briefly discussed. The stability criteria of the finite-difference schemes are analyzed by applying the von Neumann method. Numerical dissipation is studied by calculating the power attenuation along the propagation direction. Finally, the EM wave propagation and scattering in the small and medium size open-ended parallel-plate waveguide cavities are calculated by using the method, and are compared with modal solutions 相似文献
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A domain-integral equation method is presented to determine both propagation constants and the electromagnetic field distributions of guided surface wave modes in integrated optical waveguides. Both the waveguide and its multilayered embedding are anisotropic. The permittivity tensor of the embedding is assumed to be piecewise homogeneous. The kernels of the domain-integral equations consist of Green's tensors. The integral equations form an eigenvalue problem where the electric field strength represents the eigenvector. This problem is solved numerically by applying the method of moments. Numerical results are presented for an anisotropic ridge waveguide, embedded in an anisotropic multilayered medium 相似文献
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Li L.-W. Jin-Hou Koh Tat-Soon Yeo Leong M.-S. Pang-Shyan Kooi 《Antennas and Propagation, IEEE Transactions on》2004,52(2):466-477
A complete eigenfunction expansion of the dyadic Green's functions (DGFs) for planar, arbitrary multilayered anisotropic media using cylindrical vector wave functions is presented. These formulations are constructed based on the principle of scattering superposition. For the scattering dyadic Green's function in each layer, the scattering coefficients of TE and TM modes are determined from the boundary conditions matched at the planar interfaces. The explicit representation of the DGFs after reduction to the isotropic case agrees well with the existing results corresponding to the isotropic media. The general DGFs for multilayered anisotropic media are then reduced to those for a four-layered forest where the trunk layer is modeled as anisotropic medium. Application is further made for radio-wave propagation through forests of a four-layered geometry, whereas it is shown how these Green dyadic formulations are used in a practical way and how the field distributions due to a dipole can be obtained. 相似文献
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A. G. Vologdin O. K. Vlasova L. I. Prikhod’ko 《Journal of Communications Technology and Electronics》2007,52(10):1100-1103
The spatial correlation properties of the group path and the group-delay time of a radio signal leaving a random plane-layered reflecting medium similar to the ionosphere are considered. The spatial-correlation distances for the group path lying in the incidence plane and oriented perpendicularly to this plane are obtained for various angles of propagation of a wave entering the medium. It is shown that, when a radio signal is scattered by isotropic irregularities of the medium’s permittivity, regular refraction results in anisotropic fluctuations of the signal’s characteristics and the degree of anisotropy grows with the sounding angle. 相似文献
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《Microwave Theory and Techniques》1968,16(5):296-302
The complete solution of the differential equation describing the propagation of plane uniform TEM waves along the twist axis of a twisted anisotropic medium with a constant rate of twist is shown to be of exponential type, consisting of two identical pairs of independent propagation modes, each pair being associated with a particular direction of energy flow. Knowledge of the complete solution is used to solve the boundary value problem relative to wave penetration into a twisted medium at normal incidence, a numerical example being given illustrating the polarization transformation properties of the medium near the short wavelength limit. Analysis of mode properties reveals circnlar birefringence should occur in twisted media at long wavelengths. A link power, as shown by certain crystalline substances provided by the theory. 相似文献