FDTD Simulation of Electromagnetic Propagation in Magnetized Plasma Using Z Transforms

The electromagnetic propagation through a magnetized plasma slab is studied using the finite-difference time-domain method by means of the z transform The reflection and transmission coefficients of the magnetoactive plasma for the right-hand circularly polarized wave are presented. The comparison of the results of the Z transform and recursive convolution algorithms with analytic values indicates that the Z transform algorithm is more accurate than the recursive convolution algorithm. The Z transform algorithm overcomes the drawback that the recursive algorithm cannot predict the transmission coefficient of the magnetized plasma slab for the right-hand circularly polarized wave in the stop band.     

FDTD Simulation of Electromagnetic Wave Transformation in a Dynamic Magnetized Plasma

Finite-Difference Time-Domain (FDTD) algorithms are applied to study the transformation of a pre-existing electromagnetic plane wave by prescribed time variation of a cold magnetoplasma with a magnetic field along the propagation direction. A one-dimensional FDTD code is used to verify the results obtained earlier using analytical approximations based on (a) WKB method for slow switching of the plasma medium and (b) Green's function technique for rapid switching of the plasma medium. A novel successive reduction method has been developed and applied to obtain the amplitudes and the frequencies of the new modes generated by the switching of the medium.     

Simulation of Electromagnetic Wave Propagation in Plasma Using Matrix Exponential FDTD Method

The electromagnetic propagation in plasma media can be conveniently modeled using finite difference time domain method based on the matrix exponential (ME-FDTD) method. The Maxwell’s curl equations and the constitutive relations between the flux density and the electric field can be looked as a first order differential matrix system. The fundamental solution to such a system is derived in terms of matrix exponential and the update equations can be extracted conveniently from the solution. This has the advantages of presenting a more concise formulation. The ME-FDTD algorithm is validated by comparing the simulation results with the analytical values. Numerical results show that the ME-FDTD can acquire high efficiency with less computer consumption and has a good performance of flexibility and simplicity.     

任意磁化方向下磁等离子体电磁散射分析

基于电流密度拉普拉斯变换FDTD(CDLT-FDTD)方法,计算并验证了一维情况下的法拉第旋转效应、三维情况下磁化等离子体球的后向雷达散射截面(RCS),与其他方法计算结果一致.通过该方法计算并分析了任意磁化方向下磁等离子体涂敷准火箭模型的后向RCS的变化情况,计算结果表明磁化等离子体能有效减小目标的RCS.     

电磁波在均匀磁化等离子体中的衰减与反射

等离子体覆盖住金属导体,通过等离子体对入射电磁波的折射、吸收,使得入射波功率衰减,降低了反射功率,起到减小目标RCS的作用.对于均匀磁化等离子体,针对介电常数与等离子体粒子密度、外加磁场强度、电子碰撞频率以及入射波频率的关系,仿真计算了不同的等离子体粒子密度、外加磁场强度、电子碰撞频率以及不同等离子体厚度在毫米波波段对电磁波的衰减和反射特性的影响.     

瞬态电磁波在磁化等离子体中传播与散射的FDTD方法

本文从磁化等离子体中电子的广义运动方程出发，给出了一套ＦＤＴＤ计算公式，克服了卷积递归法不适用于直流入射以及小信号近似的缺点，其正确性由数值计算结果得到验证。     

用3D-FDTD法分析用于近场光存储的光纤探针电磁波传输特性

提高近场光存储的存储信息密度的关键主要在于掌握近场存储光纤探针的透光率、近场光斑直径尺寸以及场梯度等近场物理量。采用三维时域有限差分 (3D FDTD)法分析了可用于近场光存储的光纤探针尖的光学性质 ,对不同类型光纤的近场光场分布进行了数值计算 ,给出结果并进行比较 ,从光学性质的角度对其在近场光存储中的应用加以讨论。完全镀膜光纤尖在极近场处的光斑可获得 10nm的尺寸 ,远小于传统光纤光学聚焦的光斑尺寸大小。     

等离子体与电磁波相互作用FDTD 数值模拟

围绕等离子体与电磁波相互作用的问题,将气体分子动力学与电磁场理论相结合,基于玻尔兹曼方程和麦克斯韦方程建立了等离子体与电磁波相互作用自洽模型,为了对模型进行验证,将该方法与经典的电流密度卷积时域有限差分法进行对比,以一维情况下电磁波由自由空间向等离子体内传播为例,应用时域有限差分法对二者进行了数值仿真,仿真结果证明了所建立模型的正确性。此外,基于该模型仿真分析了等离子体参数对电磁波在等离子体中传播的影响,为等离子体与电磁波相互作用的研究提供了一种新思路和新方法。     

有损耗左手材料电波传播特性的FDTD分析

为研究电磁波在有损耗左手材料中的传播特性,采用时域有限差分（FDTD）法和色散媒质的Drude模型,推导出基于Drude模型的左手材料二维FDTD迭代方程。一维数值仿真结果验证了平面电磁波在穿过有耗左手材料时,其相速度大小与光速相同,方向与传播方向相反,且随着损耗因子的增大,左手材料内的电场强度幅值亦相应减小。此外,还利用多循环m-n-m脉冲作为激励源,对左手材料平板具有的完美透镜现象进行了二维数值仿真验证。结果表明,有耗平板左手材料具有明显的聚焦效果,在特定条件下能实现完美成像。     

基于拉氏变换原理的三维磁化等离子 体电磁散射FDTD分析

 根据拉普拉斯变换(LT)原理,提出了一种新的分析色散介质的电磁特性的时域有限差分(FDTD)算法,称为电流密度拉普拉斯变换时域有限差分(CLT-FDTD)算法.利用磁化等离子体介质中的关于电流密度矢量与电场强度的本构方程,将其两边分别拉普拉斯变换,得到s域内的本构方程.最后进行逆拉普拉斯变换和指数差分,得到在时域里易于求解的FDTD迭代方程.通过该方法计算了非磁与磁化等离子体球的后向雷达散射截面(RCS),验证了该方法正确性与有效性.     

电磁波在气体放电快速产生的等离子体中传播

本文根据气体放电的平均电流密度表达式，通过解麦克斯韦和波关方程，求得了电磁波与气体放电快速产生的等离子体工作用时场的表达式。并对圆极化平面电磁波进行了讨论，得到场的表达式、反射和传输系数。     

FDTD Analysis of Magnetized Plasma with Arbitrary Magnetic Declination

In this paper, the frequency-dependent finite-difference time-domain (FDTD) method employing the piecewise linear recursive convolution (PLRC) scheme is applied to the numerical analysis of magnetized plasma with arbitrary magnetic declination. The PLRC-FDTD equations are derived in detail and are checked through practical examples. Excellent agreement between the numerical results and the exact analytical solutions is demonstrated.     

用FDTD法分析和模拟三维空间电磁波的散射和传输

本文采用时域有限差分(FDTD)法计算并在PC机上模拟三维空间电磁波的散射和传输.散射体可为具有弯曲表面的三维物体,传输结构可为多介质的变向和分支型导波结构,时间波形可为单频定态波也可为任意脉冲波.在PC机上将散射近场和传输波场分布动态立体地模拟显示出来.边界上和不连续处的反射波、迅衰场、表面波和漏波等细微现象也能形象地显示出来.     

ELF/SLF电磁波传播的FDTD和GIS结合建模与分析

首次采用三维时域有限差分(3D-FDTD)经纬度模型和地理学信息系统技术(Geographic Information System,GIS)对地球-电离层波导系统进行几何建模,并对闪电、舒曼谐振中的极低频/超低频(ELF/SLF)的电磁辐射进行仿真实验.计算结果表明,当激励源放置在高空模拟闪电发生时,电磁波通过波导系统传播到观测点,并继续绕地球多次经过同一位置,直到完全衰减,其谐振频点与舒曼谐振点基本一致.发现地形地貌对于地表电磁波的电场分布有较大影响,而对地表电磁波的磁场分布几乎没有影响.     

EM Wave Propagation in Ferrite-Filled Transversely Magnetized Circular Waveguide

This paper presents a rigorous method of solving Maxwell's equations for ferrite-filled transversely magnetized circular waveguide. Solutions for cylindrical coordinate system are derived by using power series expansion of the field's potentials. Complex propagation constants are obtained by applying boundary conditions and representing fields in partial cylindrical modes. Plane wave representation of propagation is also considered. Numerical calculations of the propagation constants as well as the dominant waveguide mode reflection and transmission from a ferrite-filled waveguide section are presented.     

Electromagnetic Wave Propagation in Lossy Ferrites

The square of the complex transverse propagation constant in a lossy, magnetized ferrite is found to be described approximately by a circle in the complex plane when the magnetic field is varied. A graphical method for obtaining approximate values for the transverse propagation constant when the wave number in the direction of the applied field is given and real is derived here. This method is used to find The power absorbed from an incident plane wave by A semi-infinite ferrite as a function of the magnetizing field amplitude.     

PE模型预测蒸发波导中电波传播损耗

针对电磁波在蒸发波导中的异常传播现象,研究了电磁波在蒸发波导中的传播损耗,其传播损耗是电波传播的一个重要概念,并受到广泛关注。抛物模型(PE,Parabolic Equation Model)作为目前研究电波传播的主要模型,通过与Two-ray模型的对比分析验证了PE模型的可行性,且PE模型计算电磁波的传播损耗时可以克服其他模型预测粗糙海面时的不足。仿真分析表明,电波在蒸发波导中传播时的损耗值比在标准大气中的损耗值要小。     

基于三维的射线跟踪八叉树算法的城市微区电波传播预测算法模型

本文建立了一种有效的基于射线跟踪技术的三维城市微区电波传播预测的计算模型.该模型将计算机图形学中的八叉树分区技术扩展至射线跟踪技术,并由此提出了一种新的有效的射线跟踪算法,射线跟踪八叉树算法.并基于几何光学、一致性绕射(UTD)对场强进行计算,所得结果与实测值及FDTD的结果进行了比较.     

Electromagnetic Wave Propagation in Twisted Anisotropic Media

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.     

Propagation in Transversely Magnetized Compressible Plasma Between Two Parallel Planes

The propagation of waves in compressible single fluid macroscopic plasma between two parallel, perfectly conducting planes, with a transverse static magnetic field parallel to the boundaries is investigated. It is shown that the TE waves are not affected by either the static magnetic field or the compressibility of the plasma, while the TM wave will be affected by both.