金属包层渐变折射率平板波导传播特性

本文采用多层线型分割近似，结合欧姆损耗微扰法，分析了金属包层渐变折射率平板波导的传播特性。按此方法计算了几类典型波导的传播常数数值，结果均与精确值相吻合，且物理概念清楚，计算方法简单。     

金属包层渐变折射率平板波导传播特性

本文采用多层线型分割近似，结合欧姆损耗微扰法，分析了金属包层渐变折射率平板波导的传播特性，按此方法计算了几类典型波的传播常数数值，结果均与精确值相吻合，且物理概念清楚，计算方法简单。     

用横向谐振微扰法分析非理想波导的损耗特性

分析非理想波导的损耗特性是微波工程中很重要的实际问题之一,对它的精确求解往往和波导元件及微波系统性能的分析紧密相关。根据横向谐振原理和微扰理论,本文提出了一种分析非理想波导损耗特性的新方法,推导出了一组计算矩形波导TEm0和TE0n模导体损耗的衰减常数公式,并分析计算了矩形波导的损耗特性。通过对几种本征模式的计算,证实了本文方法的正确性和有效性。这种横向谐振微扰法具有原理简单、表达直观、计算简便易行等优点,可以更便捷地应用于解决实际微波工程问题。     

MOS型波导光学特性分析

本文分析了MOS型波导中金属包层对波导光学特性的影响,给出了TE模传播常数和吸收损耗系数的近似计算公式.为了消除由金属包层引起的吸收损耗,结合计算实例讨论了氧化物缓冲层所需厚度的选择.     

毫米波螺旋线行波管慢波系统高频损耗

基于夹持杆分层螺旋带模型和三维电磁场分析研究了毫米波螺旋线行波管慢波系统的导体和介质损耗。螺旋带模型中介质损耗考虑为纵向传播常数的虚部,给出螺旋带中电磁场的解析解,导体损耗由螺旋线和管壳表面的面电流不连续性获得。三维电磁场分析通过本征模法,求解单周期结构的品质因数和周期储能获得有限导电率导体和夹持杆陶瓷损耗角带来的慢波系统高频损耗。结果表明,毫米波段螺旋线的导体损耗和夹持杆的介质损耗远大于管壳导体损耗,介质损耗与陶瓷损耗角呈线性关系,对高频损耗的影响不可忽略。     

半导体四层漏光波导的分析Ⅱ:强耦合近似与精确解

建立了逐次微扰逼近法计算四层漏光波导的传播常数,使计算范围推到强耦合四层波导.用弱耦合近似计算结果作为初始值,在t≥0.06μm的范围获得牛顿法数值计算的收敛解,并验证了逐次微扰逼近法.由本征值方程推导了一个较好的新的微扰公式,对本文计算的波导参数,在d≥0.07μm时,它适用于t≥0.2μm的范围.     

金属包层非均匀平板介质波导传输特性分析

用微扰理论和多层分割法求得到金属包层非均匀介质波导导模的传播常数的一级和二级近似解,与用复本征方程求得的精确解进行比较,给出了与精确值符合相当好的数值结果,结果表明微扰法是相当好的近似方法,二级近似结果对一级近似结果的修正很小,一级近似已可以给出足够精确的结果。     

金属包层平板光波导在截止点附近的光学特性

本文利用二级微优近似方法分析了金属包层平板光波导在截止点附近的传输特性,将微扰近似所得的结果与本文直接求复本征方程所得的结果进行比较。结果表明,微扰法可以给出与精确值符合相当好的数值结果,并且可以给出直至截止点的解;微扰法的二级近似结果对一级近似结果的修正很小,一级近似已可以给出足够精确的结果。     

理论分析毫米波螺旋线行波管慢波系统导体和介质损耗

该文基于夹持杆分层螺旋带模型和3维电磁场模型分析,详细研究了毫米波螺旋线行波管慢波系统的导体和介质损耗。螺旋带模型中介质损耗考虑为纵向传播常数的虚部,给出电磁场的解析解,导体损耗由螺旋线和管壳表面的面电流不连续性获得。3维电磁场模型分析通过本征模法,求解单周期结构的品质因数和周期储能,获得有限导电率导体和夹持杆陶瓷损耗角带来的慢波系统高频损耗。结果表明,毫米波段螺旋线的导体损耗和夹持杆的介质损耗远大于管壳导体损耗,介质损耗与陶瓷损耗角呈线性关系,对高频损耗的影响不可忽略。     

用谱域导抗法计算铁氧体加载鳍线的传输特性

本文从Maxwell方程出发,经过Fourier变换和坐标旋转,将铁氧体中的非寻常波分解成TE和TM波,并给出它们的波导纳。利用边界条件,忽略TE和TM波间耦合的影响后,将鳍线用一等效网络表示。本文方法与T.Itoh提出的谱域导抗法比较,在等效网络中引入了理想变压器元件。最后对铁氧体加载单侧鳍线的正反向传播常数进行了数值计算,其结果与有关文献中数据吻合得很好。     

The Propagation Constants of Higher-Order Modes in Coaxial Waveguides With Finite Conductivity

Overmoded coaxial waveguides have been used in coaxial gyrotrons as a key interaction structure. To achieve the required mode selectivity, the resistivity of the center conductor is properly chosen to damp unwanted modes. Considering attenuation due to conductor loss, this study employs the perturbational method to determine the propagation constants of higher-order modes in the coaxial waveguide. The validity of the theoretical model is confirmed by comparison with results obtained using the high-frequency structure simulator (HFSS). Moreover, the method proposed herein is applied to analyze the ohmic mode selection of the coaxial waveguide.     

Rigorous analysis of the propagation characteristics of generallossless and lossy multiconductor transmission lines in multilayeredmedia

The frequency-dependent propagation characteristics of lossless and lossy open coupled polygonal conductor transmission lines in a multilayered medium are determined based on a rigorous full-wave analysis. A boundary integral equation technique is used in conjunction with the method of moments. Losses in conductors and layers are included in an exact way without making use of a perturbation approach. Dispersion curves for the complex propagation constants and impedances are presented for a number of relevant examples and, where possible, compared with published data     

A Variational Theory for Wave Propagation in Inhomogeneous Dielectric Slab Loaded Waveguides

A novel numerical technique based on the variational formulation defined only in the slab is developed to study the loaded rectangular waveguide with an inhomogeneous dielectric slab. The variational equation for the boundary value problem is formulated and solved numerically, using the finite element method with piecewise quadratic trial functions. A comparison of this new technique with the conventional variational ones is presented. Various propagation characteristics, such as the phase constant, useful bandwidth, power handling capacity, and attenuation constants due to conductor and dielectric losses, are investigated for the waveguide centrally loaded with a slab of parabolic dielectric profile. The effects of changes in dielectric profiles are discussed by examining the results for the slabs with constant and parabolic profiles.     

Propagation of short pulses in irregular electromagnetic waveguides with a variable topology of the cross section

A method for real-time electrodynamic calculation of the dynamics of propagation and transformation of short ultrawideband electromagnetic pulses (UWB EMP) in irregular waveguides with discontinuous junctions is presented. The results of numerical simulation of a pulse passing through a junction of a coaxial waveguide having doubly connected cross sections and a waveguide horn with singly connected cross sections and through a discontinuity of the inner conductor in an irregular coaxial waveguide are presented.     

Complex finite-element method applied to the analysis of opticalwaveguide amplifiers

A complex finite-element method and a three-level model for erbium ions are applied to obtain gain and propagation constants for erbium-doped waveguide amplifiers (EDWA's). The complex refractive index profile includes the effect of the dopant polarization induced by the pump field. The method allows to consider arbitrary dopant density profile as well as the modal structure of the pump field. For different waveguide geometries we obtain gain curves as function of pump intensity as well as slight variations in the modal propagation constants. The threshold pump power is shown to be a function of the waveguide geometry, which agrees qualitatively with experimental results,     

Justification of the spectral method for calculating the propagation constants of waveguides and microstrip and slotted lines

The general scheme of the spectral method for determining the propagation constants of eigenmodes in a shielded slotted waveguide is presented. The method is justified, and the general properties of the spectrum of eigenmodes in the waveguide are established.     

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.     

Calculation of the propagation constants of inhomogeneous nonlinear double-layer circular cylindrical waveguide by means of the Cauchy problem method

The problem of propagation of surface TM electromagnetic waves in an inhomogeneous Kerrnonlinear double-layer circular cylindrical waveguide is considered. It is shown that determination of the propagation constants of the considered waves is a a nonlinear conjugation eigenvalue problem for a system of two ordinary differential equations. A numerical method is proposed for determination of the propagation constants. Numerical results are reported.