On Single-Mode Bandwidth in Rectangular-Groove Guide by Finite Element Method

The single-mode bandwidth in rectangular-groove guides with different dimensions has been studied by finite element method. The actual single-mode bandwidth in a rectangular-groove guide is the same with a rectangular guide with the similiar dimensions. The dominant single-mode transmission in a rectangular-groove guide at millimetric waveband by adjusting the guide dimensions can only be an approximate one.     

Finite Element Analysis of the TE Modes in Truncated-Circular Waveguide

Truncated-circular waveguide are used in some microwave and millimeter-wave components. The field patterns in truncated-circular waveguide are desired but usually difficult to be computed by conventional methods. In this paper, they are efficiently determined by using finite element method. The electrical field lines of the dominant TE mode and the first sixteen higher-order TE modes are presented. The calculated results in this paper have important values for us to understand the transmission characteristics of truncated-circular waveguide, and will be of practical significance in designing waveguide components in microwave and millimeter wave engineering.     

Field Patterns in Double Circular-Groove Guide by Finite Element Method

The electromagnetic power coupling in symmetrical and asymmetrical double circular-groove guides have been analyzed by finite element method (FEM) in this paper. The electrical field patterns of the dominant mode and the first higher-order TE mode have been presented. The electromagnetic field of the dominant mode distributes with a concentration in the two grooves and the region between grooves as well for symmetrical double circular-groove guide, while it distributes with a concentration in the groove with larger radius for the asymmetrical double circular-groove guide. The electrical field patterns of the first higher-order TE mode in symmetrical and asymmetrical double circular-groove guide are also presented. The figures in this paper have important values in design of circular-groove guide power coupler for millimeter wave applications.     

Field Patterns of the TE Modes in Ridge-Trough Waveguide

A single-ridge waveguide with a symmetrical longitudinal trough, designated as a ridge-trough waveguide has been used as a transition in a V-band (50-75 GHz) wafer probe recently. In this paper, the field patterns for the dominant TE mode and the first higher TE mode in ridge-trough waveguide with different configurations are presented by finite element method. The field patterns in this paper have important values for us to understand the transmission characteristics of ridge-trough waveguide, and will be of practical significance in designing ridge-trough waveguide components in microwave and millimeter wave engineering.     

Field Patterns in Asymmetrical Double Groove Guide by Finite Element Method

The electromagnetic power coupling in asymmetrical double-groove guide is analyzed by finite element method (FEM) in this paper. The electrical field patterns of the dominant mode and the first higher-order TE mode have been presented. The electromagnetic field of the dominant mode is distributed with a concentration of energy in the wide groove region, while the electromagnetic field of the first higher-order TE mode is distributed with a concentration of energy in the narrow groove region. The results in this paper have important values in design of groove guide power coupler for millimeter wave applications.     

Finite Element Analysis of the Field Patterns in Elliptical Waveguide

In this paper, finite element method is first used to discuss the field patterns in a hollow perfectly conducting pipe with elliptical cross section. The electrical field lines of the dominant TE mode as well as the magnetic field lines of the lowest TM mode are presented. The results are the same with literatures, and also give a correction to the field pattern of the lowest TM mode in elliptical waveguide.     

Finite Element Analysis of Field Pattern in Multiple Groove Guide

Rectangular groove guide with multiple grooves has been analyzed by finite element method (FEM) in this paper. The electrical field patterns of the dominant mode and the first higher-order TE mode have been presented for groove guide with single-, double-, triple-, and quadruple-rectangular grooves. The electromagnetic field of the dominant mode is distributed with a concentration in the groove regions, while the electromagnetic field of the first higher-order TE mode is mainly distributed in regions between grooves. The low loss characteristic has been found not only in single-groove guide, but also in multiple groove guide.     

Finite Element Analysis of the Dominant Mode Variation in Groove Guide

In this paper, the dominant mode in groove guide is analyzed by finite element method. For the guide with a shallow groove, the electric field lines (abbreviated as E lines) are perpendicular to the parallel plate, which is different from the literatures, and the dominant mode distribution is irrelevant to the groove width; for the guide with a narrow but deeper groove, the E lines are parallel to the plate region, which represents the characteristics of lower attenuation, for the guide with a deeper and wider groove, a complicated E lines are obtained. These results reveal that the dominant mode distribution in groove guide is varied, which replenish our understanding of groove guide, and the results have important values in design, manufacture, and application of groove guide.     

Comparison of Q-Factors Between TE and TM Modes in 3-D Microsquares by FDTD Simulation

Mode characteristics of three-dimensional (3-D) microsquare resonators are investigated by finite-difference time-domain (FDTD) simulation for the transverse electric (TE)-like and the transverse magnetic (TM)-like modes. For a pillar microsquare with a side length of 2 mum in air, we have Q-factors about 5 times 10³ for TM-like modes at the wavelength of 1550 nm, which are one order larger than those of TE-like modes, as vertical refractive index distribution is 3.17/3.4/3.17 and the corresponding center layer thickness is 0.2 mum. The mode field patterns show that TM-like modes have much weaker vertical radiation coupling loss than TE-like modes. TM-like modes can have high Q-factors in a microsquare with weak vertical field confinement.     

Transmission Characteristics of Spherical TE and TM Modes in Conical Waveguides (Short Papers)

The transmission properties of spherical TE and TM modes in a perfectly conducting conical waveguide are treated in detail. To start with, an analytically simple and highly accurate digital-computer based iterative algorithm has been employed to evaluate the eigenvalues associated with the spherical TE and TM modes within the guide irrespective of the flare angle (2alpha/sub 0/) of the conical waveguide (theta < 2alpha/sub 0/ < 360/spl deg/). Subsequently, explicit expressions for the attenuation constant, phase constant, phase velocity, and wave impedance are obtained for the spherical modes transmitted within the guide. Accurate eigenvalues obtained numerically are used to study the variation of attenuation constant, phase constant, phase velocity, and wave impedance as a function of the radial distance from the apex with alpha/sub 0/ as a parameter. Measured data on the phase constant of a conical waveguide for the TE/sub 11/ mode have been compared with the analytical results obtained by calculation and an excellent agreement between the two justifies the validity of the analysis presented. Finally, a study of the phase coherence between the dominant spherical TE and TM modes within the guide is presented which may be fruitfully employed in the design of dual-mode conical waveguides.     

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.     

A Method for the Study of TE and TM Modes in Waveguides of Very General Cross Section

A simple method for the study of wave propagation in uniform hollow waveguides of very general cross sections is proposed. The method is based upon the concept of contour lines of electromagnetic field components on a typical cross section of the waveguide and applies when the boundry of the cross section of the guide is a closed curve. Examples show that values of cutoff frequencies can be obtained easily to a useful degree of accuracy.     

矩形槽波导的模式图

本文用有限元法分析了矩形槽波导。对矩形波导的计算验证了我们的有限元程序是有效的。文中给出的矩形槽波导模式图有助于设计基于矩形槽波导的短毫米波和亚毫米波器件。     

印刷电路板温度-应力耦合场有限元分析

温度和热应力是引起印刷电路板功能失效的重要原因,针对某电子设备的PCB。对其温度-应力耦合场进行有限元分析,找出了印刷电路最大可能的失效区域;采用DOE方法对元器件结构布局进行了优化设计,使离面正负最大变形量达到最小值,应力集中得到了改善,提高了PCB的使用寿命。     

导轨龙门架有限元分析及辅助系统设计

针对传统导轨龙门架设计周期长、效率低、精度难以得到保证的问题,文中采用Ansys Workbench进行了相关分析和计算,并进行相应的物理实验验证了分析结果的准确性,通过Matlab插值拟合计算,获取区间段内的连续结果,并采用了SQL数据库以及基于.net平台的C#编程技术,将上述各项结果进行数据库的整合,最终搭建了前台辅助系统。该系统方便了设计人员对导轨龙门架的设计过程,提高了设计精确性,并缩短了研发周期,对新产品的设计研发提供了一种新的思路。     

On the Electric Field Lines of the Dominant Mode in Millimetric V-Groove Guide by Finite Element Method

In this paper, the electric field lines of the dominant mode in a closed V-groove guide as well as an open one are analysed by finite element method. The results show that the electric field lines are not parallel to the parallel plate region, but perpendicular to them. Since the attenuation increase with increasing frequency when the electric field lines are perpendicular to the mental walls, the V-groove is not suitable to be used in millimeter and submillimeter wavebands, and it is can't be regarded as low-loss wave guiding structures.     

连续扫描激光钎焊温度场有限元分析

利用ANSYS软件对激光钎焊过程温度场进行了有限元模拟,在分析过程中采用三维单元,并考虑了材料热物性的非线性特征,建立了有限元模型,得出了钎焊过程中,不同工艺参数下试样表面、截面的温度场分布图,并进行了温度测量和实际钎焊实验.结果表明,有限元分析温度曲线与实测温度曲线比较吻合,钎焊后金刚石与基体实现高强度连接,对钎焊过程选择工艺参数具有很大的指导意义.     

Analysis of Finite Conductivity Cylindrical Conductors Excited by Axially-Independent TM Electromagnetic Field

A method is presented for the analysis of a system of cylindrical conductors, of large but finite conductivity, situated in a uniform dielectric and excited by an axially-independent TM electromagnetic field. The analysis is based on separating the space into the region exterior to the conductors and regions interior to the conductors, placing equivalent electric and magnetic currents on the boundary surfaces, applying the boundary conditions for the tangential fields and, hence, obtaining a system of coupled integral equations. Due to the special geometry and the chosen excitation, the problem treated is a two-dimensional one. The distribution of the unknowm surface currents is approximated by pulses, and the amplitudes of these pulses are determined by a point-matching technique. This method is applied to the problem of determining the inductance and resistance of two-wire transmission lines.     

Analysis of TE and TM modes in DFB lasers by two-dimensional theory

The two-dimensional theory of a distributed feedback (DFB) laser (which was previously presented and applied to the analysis of the laser threshold conditions for the transverse-electric (TE) mode in a simple three-layer waveguide structure) is developed to treat both TE and transverse-magnetic (TM) modes in a four-layer waveguide structure with a thin grating layer, which more closely reflects actual DFB laser structure. The differences between TE and TM modes for the dispersion relations and the laser threshold conditions are clarified. The effects of the waveguide structure (including grating layer thickness, refractive indexes of layers, coupling constant, and corrugation period) on the threshold gains and the gain differences between the two longitudinal modes on both sides of the Bragg frequencies are studied in detail for both TE and TM modes     

基于Matlab的电场有限元数值计算分析

有限元法是对电磁场进行数值求解的重要方法,也是本科电磁场课程的教学内容之一.论文结合本科教材阐述了对电场进行有限元计算时的数学模型和算法原理,介绍了Matlab软件基本的矩阵处理编程方式和电场场域有限元分析的算法框图.进而联系教材中一个电器的电场电位分布计算实例,在Matlab环境下进行有限元计算编程的实现.数值解与解析解的比较结果表明Matlab应用在对电磁场进行有限元计算所具备的合理性与简易性.本文对本科教学中帮助学生理解电磁场的数值计算及其编程实现有一定的参考意义.