Characteristic electromagnetic waves in a circular waveguide filled with a biisotropic medium

A numerical solution is given for the problem of characteristic electromagnetic waves in a circular waveguide with a biisotropic rod. The dependences of the propagation constants of the different wave modes on the chirality parameter, nonreciprocity, and permittivity of the rod are obtained. The results presented can be useful when developing devices and measuring the parameters of biisotropic materials. State University, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 48–52, February, 1997.     

The field distributions and dispersion characteristics in chiroferrite central-loaded waveguide

The field distributions and dispersion characteristics of hybrid modes in circular chiro ferrite central-loaded waveguide are investigated numerically in this paper. Especially, the effects of constitutive parameters of chiro ferrite material on the propagation behaviour of hybrid modes are examined in detail, and some novel features are pointed out. The results show that, as reciprocal chiral and gyrotropic media, nonreciprocal chiroferrite materials have potential applications for the design of microwave, millimeter wave and integrated optical devices.     

电磁波在负折射材料填充的3层平板波导中的传播特性

从电磁场理论出发对负折射材料填充的3层平板波导的传播特性进行研究,并进行了数值计算,分析TE和TM波在平板中传播的性质,得到了电磁波的模式方程,与电磁波在右手材料填充的平板波导中的传播特性做了对比,考察了TE模式的能流密度,进行了归一化计算。结果分析表明：基模、一阶模不存在,且任何模式都存在一个截止厚度,随着厚度的增大,模式数量也增多;在一定的入射频率下,平板薄膜厚度趋向一定数值时,可以同时传播多种模式的波,并且入射波频率越高,波导同时存在多种模式的可能性越大;与右手材料相比,左手材料填充相同尺寸的3层平板波导可以传播更高能量的电磁波,导波效果更好。     

基于Drude-FDTD算法的单负介质组合填充波导传播特性研究

提出了电单负介质和磁单负介质组合填充矩形波导结构,通过理论分析和修正的3D-Drude-FDTD算法进行数值仿真,分析了电磁波在其中的传播特性.仿真结果表明,新结构波导中存在异于传统介质填充波导的亚波长导模,且传播常数基本不随频率的变化而变化,可以用于宽带微波器件和天线的设计. 关键词： 单负介质 传播常数 截止频率 时域有限差分法     

Propagation and radiation characteristics of the circular electric, circular magnetic and hybrid waveguide modes

The field distributions and propagation constants of the circular electric, circular magnetic and hybrid modes of oversized waveguides are expressed, taking the effects of walls into account. These effects are described by wall functions which depend on surface impedances of the wall, and are determined for different types of guides. The near and far field patterns are derived in the case of real wall functions. It is shown that, for very oversized waveguides, the terms containing wall functions can be ignored in the calculations, and it results that the expressions of fields and propagation constants become independent of the types of waveguides. An application to corrugated waveguides for Electron Cyclotron Resonance Heating experiments shows the variations of the radiation characteristics versus geometric parameters of the corrugations and determines the ranges of interest for these parameters.     

各向异性超常媒质矩形波导的导波特性研究

研究中通过建立和求解填充各向异性超常媒质的矩形波导TE模式和TM模式的波动方程和场分布方程,讨论了各向异性超常媒质矩形波导的有效介电常数、有效磁导率、相位常数以及传输系数与所填充超常媒质本构参数之间的变化关系.研究发现,填充了各向异性超常媒质的矩形波导的导波特性在截止频率之上的频率区域,其导波特性由所填充超常媒质的横向本构参数决定,而与超常媒质的纵向本构参数无关.但是,在截止频率之下的频率区域,该矩形波导的导波特性则由所填充超常媒质的横向本构参数和纵向本构参数共同决定.研究中通过典型的计算实例对所得到的结 关键词： 各向异性 超常媒质 矩形波导 导波特性     

孔隙介质包裹的充液管道结构中导波传播特性

研究孔隙介质包裹的充液管道中纵向导波传播特性,分析孔隙介质参数对频散曲线的影响。建立了孔隙介质包裹充液管道的结构模型,利用孔隙介质弹性波动理论,建立对应的频散方程,数值模拟计算得到该模型的频散曲线和时域波形,并分析了孔隙介质参数以及管壁厚度对频散曲线的影响。结果表明孔隙介质的渗透率对于导波频散的影响较小,孔隙度的改变对时域波形的位移幅度影响较大。同时,导波存在衰减,且衰减随孔隙度增大而增大。所得结论为埋地管道无损检测方面提供一定理论参考。     

Propagation characteristics of guided waves in a liquid filled pipe embedded in a porous medium

A model of a liquid-filled pipe embedded in a porous medium is built to research its wave propagation characteristics,and to analyze the effect of the parameters of porous media on the dispersion.The dispersion equations are established on the basis of the elastic-dynamic theory of the liquid-saturated porous solid.The characteristic of dispersion and the time domain waveform in pipes of different thicknesses and with different porous-medium parameters are discussed theoretically and numerically...     

Cerenkov radiation fields in an inhomogeneously filled circular waveguide

Cerenkov radiation fields excited in a partially filled circular waveguide with a channel in which an electron beam propagates are studied. The surface of the channel is covered by a thin quasi-conducting layer to remove the electrostatic charge due to the beam passage. The effect of the thickness of the cylindrical dielectric layer is investigated. The thin quasi-conducting layer is shown to attenuate the Cerenkov waves generated in the lossless medium only slightly.     

Transition radiation of a charged particle crossing the waveguide filled with a dispersive dielectric medium perpendicularly to the waveguide axis

The theory of charged particle transition radiation is developed for the case when the particle crosses the waveguide, which is filled with a piecewise-homogeneous dielectric, perpendicularly to the waveguide axis. The cases where the charged particle is flying between two dispersive plates and between two thin impedance films are considered.     

高功率微波在等离子体填充波导中的传播特性

 在考虑有质动力情况下对高功率微波在等离子体填充波导中的传播特性进行了理论分析和数值计算,研究了高功率微波在等离子体中的传播特性和微波场强与等离子体密度分布之间的关系。结果表明高功率微波的有质动力将影响微波色散特性,使微波场强分布偏离Bessel分布,并对等离子体有排开作用,当场强足够大时可将波导中心处等离子体排空形成低密度通道。     

外开槽同轴波导传播特性

 根据满足边界条件的一系列电磁场方程,采用场匹配法,详细推导了外开槽同轴波导的特征方程。在外开槽同轴波导光滑内同轴半径等于零的情形下,即变成外开槽圆波导,得到其特征方程。数值模拟了外开槽同轴波导及外开槽圆波导中TE₀₁模式的传播特性,得到了不同尺寸外开槽同轴波导开槽间隙半张角和槽深与特征根的变化关系。结果表明:开槽越深,间隙半张角越小,特征根值越小。     

Transmission characteristics of wave modes in a rectangular waveguide filled with anisotropic metamaterial

In this paper, transmission characteristics of wave modes in a rectangular waveguide filled with lossless anisotropic metamaterial are theoretically investigated. The wave equation and dispersion relations for TE and TM modes in the waveguide are obtained and analyzed. It is shown that the negative constitutive parameters of the filling anisotropic metamaterial can be used to control the wave magnitude and the phase velocity direction in the waveguide over the entire frequency domain, both below and above the cutoff frequency. Particularly, not only backward waves, but also forward waves can propagate below the cutoff frequency in the waveguide. Furthermore, a typical example is calculated to demonstrate transmission characteristics of waves inside the waveguide. Numerical results are obtained in the paper and compared with theoretical predictions: a good agreement is found.     

等离子体填充波纹波导中低频模式特性分析

采用等离子体流体模型和线性场理论，导出了在强引导磁场下，一无限薄环形等离子体加载 波纹波导中电磁波传播的色散关系.数值计算并分析了在不同的等离子体填充密度下，低频 等离子体模式的色散特性和行波管的小信号增益.研究发现，低频等离子体模式可与相对论 电子束发生同步互作用使高频信号放大.同时，在无限薄环形等离子体填充条件下，波纹波 导中的低频等离子体模式严格满足Floquet定理所要求的周期性，其上截止频率不再受到等 离子体频率的限制，当密度较大时，等离子体模式还可与TM模式发生耦合. 关键词： 等离子体 波纹波导 色散关系 增益