多层环状导电媒质中离轴偶极子辐射场的级数解

当偶极子源(电偶极子或磁偶极子)置于多层环状导电媒质中偏离轴线的任意一点时,所激发的电磁场既存在TE波又存在TM波。文中导出了各层媒质中电磁场的通解,用边界条件建立了系数传递矩阵,从而完全确定了电磁场表达式。计算实例中给出了一组离轴偶极子的响应曲线。     

用COMSOL实现圆波导中电磁波的可视化

为了直观描述金属圆波导中电磁场复杂的空间分布,本文用Comsol软件对金属圆波导中的TE11模、TE01模、和TM01模的电磁场结构进行动态仿真.将电磁场中的抽象概念形象化、可视化,使学生看清电磁场分布的宏观概况和细节变化,开拓了视野,同时加深了学生对电磁波传播特性的理解.     

矩形波导TE10模的仿真与分析

针对矩形波导TE10模的特点,为了提高电磁设计性能,设计出矩形波导TE10模的仿真模型。本文首先根据电磁场传播理论,采用直角坐标系分析对无源自由空间电场和磁场采用矢量亥姆霍茨方程分析,得出矩形波导中传输模式及其场分布,然后分析了矩形波导中传输模式的纵向传输特性,最后利用HFSS软件对矩形波导TE10模的场结构进行三维空...     

色散对圆柱形光子晶体波导传输模式的影响

利用材料的色散关系和特征矩阵法研究了一维圆柱形光子晶体波导中TE波和TM波模式禁带的变化特征,得出了TE波和TM波模式禁带随色散强度、色散厚度的变化规律.色散强度和色散厚度都会对一维圆柱形光子晶体波导中TE波和TM波的模式禁带产生影响.利用TE波和TM模式禁带随色散强度、色散厚度的变化规律,可实现对一维圆柱形光子晶体波导中TE波和TM波各传输模式的有效控制.     

1维方形掺杂光子晶体波导中缺陷模的色散特性

为了研究1维方形掺杂光子晶体波导中缺陷模的色散,采用特征矩阵的方法研究了1维方形掺杂光子晶体波导中TE波和TM波缺陷模的变化特征,得到了TE波和TM波的缺陷模随色散强度、色散厚度变化的结果。结果表明,色散强度和色散厚度都会对1维方形掺杂光子晶体波导中TE波和TM波的缺陷模产生明显的影响;利用TE波和TM波的缺陷模随色散强度、色散厚度的变化规律,可以有效地实现对1维方形掺杂光子晶体波导中TE波和TM波各传输模式的有效控制。     

电磁波泵浦的自由电子激光器

本文研究了电磁波泵浦的自由电子激光器。从跃变磁场结构出来的大半径迴旋环形电子束通过圆柱形波导与圆柱形波导的TE11模入射电磁波相作用。利用电子束的弗拉索夫分布函数理论和三维波导模的波动方程求得在康普顿区域中的散射波色散关系。通过数值分析,讨论了轴向引导磁场,电子束能量,电子迴旋比和电子束环的径向位置等与散射波频率和增长率的关系。     

过模弯曲圆波导模式耦合设计

基于耦合波理论,波导轴线采用常规圆弧弯曲和改进的正弦弯曲结构,对TE01—TM11模式变换器进行全面优化分析,计算中考虑了多模、反向波、金属壁所带来的欧姆损耗以及相位重匹配等因素.以正弦弯曲设计的Ka波段TE01—TM11模式变换器的转换效率达到99%,带宽超过32%,并得出常弯曲结构中波导半径、波导曲率、变换器长度和转换效率之间的关系.     

自由电子激光器的横向几何效应

以具有轴向磁场和线偏振摆动器场的自由电子激光器为例研究了波导壁和电子束厚度对自由电子激光不稳定性的影响。用流体力学方法推得了辐射波(TE模)和TM模的耦合方程组,将解得的电磁场代入电子束表面的边界条件便得到色散关系和不稳定性的增长率。数值结果表明体耦合的贡献远大于面电流密度耦合的贡献。存在一个最佳厚度和波导壁距离,此时增长率为极大。     

法拉第磁光波导的耦合模分析

利用法拉第磁光效应可以设计光纤磁场传感器。在磁场传感过程中，磁光晶体薄膜波导的TE模和TM模式之间将发生转换，：其转换效率与磁光晶体的法拉第旋转角度和双折射有关。本文建立了磁光波导的耦合模方程，分析了磁光波导中的TE—TM模转换，提出了通过减小线性双折射和增大法拉第旋转角来提高TE—TM模耦合效率的措施，这些措施有利于增大光束TM模的输出功率并提高光纤磁场传感器的灵敏度。     

一种使用TE11为过渡模的TE01-HE11模式变换器设计

基于弯曲圆波导耦合理论和规则圆波导突变结构模式匹配法, 利用MATLAB软件编写的相关数值计算程序得到波导模式转换结构的优化参量, 最终使用CST软件对模型进行了仿真和验证.该系统主要由三部分组成: 一个TE01-TE01的过渡器, TE01-TE11和TE11-HE11的圆波导模式转换器.计算结果表明, 该TE01-HE11模式转换系统在24.13 GHz的频率有5%的带宽、转换效率超过了99%.计算结果、仿真结果和实物冷测结果是一致的.     

Electrodynamic analysis of eigenmodes in a rectangular waveguide with two L-shaped septa

A technique of electrodynamic calculation and computer-aided simulation of the structure of the electromagnetic fields of TE and TM waves in a rectangular waveguide with two L-shaped ridges and a lossless air filling is presented. The problem is solved by means of the partial domain method with allowance for the edge singularity of the electromagnetic field. Cutoff wave numbers, the structure of the electromagnetic fields of various TE — and TM-wave modes in the cutoff regime, the characteristic impedance, and the breakdown power for the fundamental waveguide mode are calculated.     

A multipole analysis of a dielectric loaded coaxial rectangularwaveguide

A multipole analysis of a coaxial rectangular waveguide whose inner conductor is circular is made in order to determine the TE and TM modes of the system. The analysis is based on using multipole (dipole, quadrupole etc.) electric and magnetic current sources to generate field solutions in the waveguide. These solutions are used to match the electromagnetic boundary condition in a homogeneous coaxial rectangular waveguide and to determine the TE and TM eigenvalues of the waveguide system. Eigenvalue results are compared with results of the generalized spectral domain method and to eigenvalue results for a ridged waveguide. Propagation in a coaxial rectangular waveguide is also studied when the coaxial rectangular waveguide is loaded with lossy inhomogeneous dielectric material. A variational formula is used to relate the TEM, TE, and TM modes of an empty coaxial rectangular waveguide to the propagation in the loaded inhomogeneous dielectric waveguide     

矩形波导中主模电磁波传播特性研究

矩形波导主模电磁波是波导传输中使用最多的模式。为了能深入了解其传播特征。从波导的截至波长入手,讨论了电磁波单模传播的条件。得出结论：主模传播需要电磁波波长和波导尺寸之间满足一定关系。推导出主模电磁波的场方程,利用该场方程,结合一定尺寸的矩形波导管,模拟出一定频率的主模电磁波分布图,进而总结了主模电磁波传播的主要特征。这...     

矩形隧道中的列车对电磁波截止频率的影响

将隧道看作波导，利用有限元素法，分析了矩形隧道中的列车对电磁波截止频率的影响，可知列车的存在使TE波模的截止频率降低，使TM波模的截止频率升高。     

The theory of propagation of electromagnetic waves in a waveguide with a magnetoactive anisotropic modulated filling

Propagation of electromagnetic waves in a waveguide with an arbitrary cross section is considered. The waveguide is filled with a magnetoactive anisotropic medium periodically modulated in space and time. The wave equations for the potentials of transverse electric (TE) and transverse magnetic (TM) fields are derived. Expressions for the TE and TM waveguide fields observed in the region of weak interaction between the signal wave and the modulation wave are found in the first approximation for small modulation indexes of the filling. The frequency near which strong (resonance) interaction between the signal wave and the modulation wave develops is expressed in an analytic form. The propagation of TE and TM waves in the strong-interaction region is investigated.     

基于矢量波函数空间算子理论的波导系统有限元分析

该文介绍了一种能够消除非物理模的波导系统的有限元分析方法,从矢量波函数空间的偏微分算子理论出发,推导出具有简洁而自洽数学形式的完备的电磁波基本方程组,将电场矢量用两个标量函数表示,并用有限元法对这两个标量函数进行数值求解,从而得到了波导系统的有关参数,文中以加载膜片波导和E面矩形波导阶梯为例说明了这一分析及计算过程。     

Scattering at Circular-to-Rectangular Waveguide Junctions

A formally exact solution is given for the problem of scattering at a circular-to-rectangular waveguide junction and at a thick diaphragm, with a centered circular aperture, in a rectangular waveguide. The method uses normal TE and TM mode expansions of the waveguide fields and traditional mode matching of the transverse electric and magnetic fields at the junction boundary. Exact closed-form expressions are obtained for the electric field mode-matching coefficients which couple the TE(TM) modes in the rectangular guide to the TE(TM) and TM(TE) modes in the circular guide. Numerical results are presented for the case of TE/sub 10/ mode propagation in the larger rectangular guide with all other modes cutoff. Convergent numerical results for the equivalent shunt susceptances of such junctions are obtained when about 12 modes (eight TE and four TM) are retained in the circular waveguide or in the circular aperture of the diaphragm. The results are graphically compared with formulas and curves due to the quasi-static theory of Bethe and the variational theory given in the Waveguide Handbook [2].     

On Guided Waves in Moving Anisotropic Media

Based upon the Maxwell-Minkowski theory, the equations governing the propagation of electromagnetic waves in a cylindrical waveguide of an arbitrary cross section filled with a moving anisotropic medium are derived. The governing equations are reducible to a pair of coupled wave equations in the axial components of the electric and magnetic fields, which in turn can be solved through the solution of a single second order scalar homogeneous Hehnholtz equation. For a general anisotropic medium no pure TM or TE modes can exist in the waveguide. However, if the moving medium is uniaxially anisotropic, TM and TE modes are possible. It is interesting to note that the cutoff frequencies are always lowered by a factor which depends upon the velocity of the medium and is independent of the guide geometry. The formulas for the characteristic wave impedance and power flow in a waveguide for a moving uniaxial medium, if expressed in terms of the new cutoff frequency, have the same forms as those for a moving isotropic medium. The propagation characteristics of waveguides of rectangular and circular cross sections filled with a moving uniaxial gyroelectric medium are discussed.     

三层介质波导中TE波的转移矩阵及场分布研究

从TE波的波动方程出发,根据电磁场的边界条件,推导出了三层介质平板波导中电场的表达式,得到了波导层TE波的转移矩阵和模式本征方程,并计算出了光波的功率流密度分布,通过对传输功率流的分析得到:在平板介质波导中,传输电磁能量的厚度大于薄膜的实际厚度.最后用Matlab描绘的本征值图对场分布进行了研究,从图中得到:在对称平板波导中没有截止厚度和截止频率,而非对称平板波导中存在截止厚度和截止频率,薄膜厚度越大,能承载的导模数越多.