Analysis for Transmission Characteristics of Closed Trapezoidal-Groove Waveguide with Boundary Element Method

In this paper, the cut-off and dispersion characteristics of a new kind of closed trapezoidal-groove waveguide that has more advantages than open groove waveguides are analyzed with the help of the boundary element method, the relationship between cut-off wavelengths and variations of guide's relative sizes is discussed in detail. The calculated results are in good agreement with those in the relevant reference. So, the obtained conclusions are very important in theoretical studies and actual applications of closed trapezoidal-groove waveguides for millimeter and submillimeter waves.     

On the Dominant Mode in Closed Trapezoidal-Groove Guide by Finite Element Method

The structure of closed trapezoidal-groove guide is similiar to that of open one, but it can be used to prevent energy from leaking out of the guide. In this paper, the propagation characteristics of dominant mode in closed trapezoidal-groove guide are analysed by using finite element method and the results are discussed.     

Mode Distribution and Bandwidth Characteristic of Arbitrarily Trapezoidal-Groove Guide for Millimeter Waves

The modes TE and TM of arbitrarily trapezoidal-groove guide are analyzed by using the mode-matching method. The mode TE₁₁ is the dominant mode of the trapezoidal-groove guide under different conditions. The bandwidth characteristic and the operation condition for the single dominant mode are discussed. The obtained conclusions are of very important significance in theoretical study and practical application of trapeziodal-groove guides for millimeter waves.     

Analysis for Transmission Properties of Arbitrarily Trapezoidal-Groove Waveguide for Millimeter Waves

In this paper, the transmission properties such as the dispersion and attenuation characteristics for the dominant mode of the trapezoidal-groove waveguide with arbitrarily inclined angle are analyzed and discussed by using the mode-matching method. Some calculated results are in very good agreement with the published data. The obtained conclusions are of important significance in theoretical studies and actual applications of trapezoidal-groove waveguides for millimeter and submillimeter waves.     

ANALYSIS OF ARBITRARILY TRAPEZOIDAL-GROOVE GUIDE WITH THE CONFORMAL MAPPING METHOD

The arbitrarily open trapezoidal-groove guide is analyzed with the conformal mapping technique. A new formula is given for the evaluation of one fundamental parameter associated with the technique. The relationship between the cut-off wavelength for the dominant mode and the geometry of the guide structure is studied; dispersion characteristic of the groove guide is also given. Some numerical results are shown to be in good agreement with both experimental data and the results of the finite element method (FEM). Moreover, it is testified that dispersion of the trapezoidal-groove guide is low. The obtained results are significant for the design and application of the open trapezoidal-groove guide for millimeter waves.     

On the Main Mode of Trapezoidal-Groove Guide By Finite Element Method

In this paper, the propagation properties such as the dispersion characteristics, cut-off wavelength, guide wavelength and field distribution for the main mode of trapezoidal-groove guide are analysed by using the finite element method. The dispersion is very low, and the field distribution in a trapezoidal-groove guide is similar to that of rectangular one. The results have important values in design, manufacture, and application of groove guides.     

Study on Transmission Characteristics of Trapezoidal-Groove Guide with Mode-Matching Method

In this paper, the dispersion, cut-off and attenuation characteristics of trapezoidal-groove guide are analyzed by using the mode-matching method. The relationships between the guided parameters and variations of relative guide's sizes are discussed in detail. The calculated results are in good agreement with those in relevant reference. So, the obtained conclusions have important values in theoretical studies and actual applications of trapezoidal-groove guides for millimeter and submillimeter waves.     

An improved solution to the dominant mode properties of groove guides of general cross section

An improved solution to the dominant mode properties of groove guides of general cross section is presented in this paper. A novel differential equation is formulated and solved by numerical integration technique. Numerical results for single V-groove guide show good agreement with available measured values. Calculated results for the cutoff wavelengths of semicircular-groove and trapezoidal-groove guides are presented.     

Analysis for dispersion characteristics of trapezoidal-groove waveguide

In this paper, the dispersion characteristics of the main mode for the trapezoidal-groove guides are analysed by using the approach of equivalent network with transverse resonance. The relationship curves between guide wavelength, phase constant and guide dimensions, frequency are obtained. The characteristics have important values in design, manufacture and application of groove guides.     

A Multilayer Waveguide Window for Wide-Bandwidth Millimeter Wave Tubes

A multilayer waveguide window is demonstrated to exhibit wide bandwidth and high transmission for applications in high-frequency microwave tubes. A transfer matrix approach is employed to discretize the dielectric function profile of the multilayer heterostructure in a rectangular waveguide. The closed form has been obtained and the corresponding reflection and transmission characteristics have been carried out. The analytical calculation is also compared with the result of numerical simulation via the finite-element code HFSS. The exact calculation agrees with the numerical simulation very well. By comparison, the approach not only enhances the accuracy and efficiency, but also gives a good criterion for the design. The results show that the bandwidth for a transmission of 99%, i.e., S ₁₁ below –20 dB, can be optimized to be about 8.75 GHz at a central frequency of 35 GHz or about 25%. A wide-bandwidth waveguide window can be easily designed for Ka-band and W-band tubes, and even for higher frequency ones.     

Eigenmode analysis of anisotropic optical fibres or integrated optical waveguides

Using the finite-element technique, the eigenmodes propagating in an inhomogeneous, anisotropic optical waveguide with arbitrary cross-section are computed. The method is based on a variational principle for the modes of an anisotropic dielectric waveguide. It is shown that very accurate results are obtained, even for the guides formed by very small changes in the refractive index. As an example, the propagation characteristics of a channel guide embedded in LiNbO3 are computed.     

Numerical Analysis of the Rectangular Dielectric Waveguide and its Modifications

Dielectric waveguides suitable for millimeter and submillimeter wave integrated circuits are analyzed by applying the generalized telegraphist's equations. The dielectric waveguides treated in this paper are the rectangular dielectric image line, the cladded rectangular dielectric image line, the insulated image guide, and the strip dielectric guide. Numerical results of the propagation constant, the power distribution, and the field configuration in these dielectric waveguides are presented. Values for the propagation constants obtained by our method are compared with other theoretical results. Although this work is based on a closed waveguide model, it may be applicable to wide classes of dielectric waveguides with arbitrary dielectric profiles and cross sections.     

The design of a mode selective directional coupler for a high power gyroklystron†

The design method of mode selective directional couplers from a transverse electric mode in a circular waveguide to the fundamental mode in a rectangular wave guide is presented in this paper. The design results for a TE₀₁ circular mode coupler intended for use in the output power measurement of a high power gyroklystron are reported; these results indicate that more than 50-80dB directivity and sufficient suppression of unwanted modes can be obtained with a coupler less than 07m in length. The effects of frequency and rectangular wave guide size on coupler parameters are also discussed in this paper     

Generation of millimeter wave Gaussian beams and their propagation in a dielectric waveguide

Linearly polarized fundamental mode Gaussian beams were generated and coupled to a hollow circular oversized dielectric waveguide by placing the waist of the beam at the guide entrance. The transmission properties of the waveguide were characterized as a function of frequency for a variety of coupling conditions. These conditions included changes in the input beam waist radius, angle of incidence, and displacement perpendicular and parallel to the guide axis. It has been found that: 1.) power transmission is maximized when the waist of the input beam is centered at the guide input, injected normally, and has a radius of 0.43 times the waveguide radius, 2.) power transmission decreases rapidly with increasing angle of incidence and the rate of that loss increases with frequency, 3.) the waveguide preserves the linear polarization of the input beam, 4.) power transmission in the fundamental waveguide mode is not greatly affected by moderate displacements in the input beam position, and 5.) upon exit from the waveguide the launched EH₁₁ mode propagates as a fundamental mode Gaussian beam in the quasi-far field. The results compare favorably to the transmission theory of Belland and Crenn and approximately to the near and far field mode pattern theory of Degnan.     

不对称脊波导的传输特性

提出了用有限差分方法分析不对称脊波导主模的截止波长和场结构图等传输特性,推导出用有限差分方法计算相关参数的公式。脊波导中主模的截止波长可随脊位置的变化而变化。文中编程计算了不对称脊波导、L型波导脊位置变化时截止波长和场结构的变化规律,给出了计算数据和曲线图。计算结果与相关文献非常吻合,证明文中提出的计算方法和计算结果是正确和可行的。     

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.     

On grating-coupled radiation from waveguides

We show that grating coupled radiation from a waveguide is a very sensitive oscillatory function of waveguide thickness when substrate and guide indices differ greatly. Because of this phenomenon, computed results are strongly dependent on the choice of waveguide geometry used to calculate the unperturbed modes.     

有限尺寸介质基片上的共面波导

有限尺寸介质基片上的共面波导是一种非常接近于工程应用状态的物理模型.本文用共形映射技术分析有限尺寸介质基片上的共面波导,得到了它的单位长度电容、有效介电常数和特性阻抗等基本参数,与介质基片宽度为无限大的理想化模型作了比较,给出了介质基片为多宽可以认为是无限宽的判别公式.     

TEM Impedance and Cross Coupling for Small Circular Center Conductors in a Double Ridged Waveguide

The even and odd mode TEM impedances and crosscoupling coefficient were found for two small circular center conductors in a double ridge waveguide structure. Expressions were found by the use of a variational approximation for the case where the centers of the circular conductors lie on the horizontal center line of the guide; the conductors were placed symmetrically about the vertical plane of symmetry of the guide, and the conductors were placed a reasonable distance from the guide and from the region between the ridges. Results calculated from these expressions agree reasonably well with experimental data. The experimental and theoretical results tend to indicate that proper placement of the two conductors in a double ridge guide could be used as a method of transmitting three different messages inside a single closed waveguide.     

Double-Ridge Waveguide for Commercial Airlines Weather Radar Installation

This paper describes the design and development of a double-ridge waveguide designed to propagate both C-band and X-band (5,400 and 9,300 mc) so as to allow for a common waveguide installation in commercial airliners which could use either a C-band or an X-band weather penetration radar. This double-ridge waveguide is capable of propagating over the desired frequency range with single mode operation only; it yields attenuation at C-band which is only slightly higher than that of normal C-band waveguide and has somewhat reduced attenuation at X-band compared to standard 1 X 1/2 rectangular waveguide. This double-ridge guide has been adopted by Aeronautical Radio, Inc. and is specified in their Characteristic No. 529 entitled "5.7 Cm Weather Penetration Airborne Radar." This paper also gives an analysis of the calculated guide wavelength in this double-ridge guide, attenuation, and peak power-handling capabilities; and compares the results of these calculations with measured data. Peak power-handling capability for this double-ridge guide is well within the requirements of this application. The testing procedures used for high-power breakdown measurements are described. This paper also covers the development of double-ridge waveguide flanges, elbows, bends, twists, transitions, and flexible waveguide for use over this extremely broad band.