Rigorous Analysis of Electromagnetic Wave Propagation in Cylindrical Dielectric Waveguide Array

Cylindrical Dielectric Waveguide Array(CDWA) should be considered as a kind of two-dimensionally periodic(2DP) medium. Based on the established rigorous theory for 2DP medium, a great amount of numerical results for CDWA were presented. Wave propagation in CDWA was analyzed in detail in this paper. Firstly, given the longitudinal wave vector (k _z=0), Brillouin dispersion relations between transverse wave vectors were analyzed when modulation coefficients or the rate of different dielectric areas in a unit cell varied. Interactions between space harmonics were also studied. Secondly, when the area of dielectric cylinder in the unit cell varied within a given range, CDWA dispersion relations were compared with Rectangle Dielectric Waveguide Array's, some interesting conclusions were obtained.     

Transverse Propagation in Dielectric Waveguide Array

Transverse propagation eigen equations for dielectric waveguide array (DWA) are derived and eigen solutions can be uncoupled into TE and TM modes. Numerical results shows that much stronger space harmonic interaction exists so that a series of interesting physical effect of canonical two-dimensionally periodic (2DP) medium can obviously be observed in DWA and related devices can be predicted, designed and realized much easier.     

Purely Longitudinal Guidance in Dielectric Waveguide Array

Rigorous analysis shows that independent longitudinally guided TE and TM modes are possible in dielectric waveguide array (DWA) as a two dimensionally periodic medium. Especially, purely longitudinally guidance is also possible and investigated in detail.     

介质波导阵列的横向传播特性分析

根据已提出的有关二维周期介质严格分析理论，针对介质波导阵列进行了大量的数值计算。对介质波导阵列中波的横向传播作了详细分析。首先，在给定纵向波矢量(k)的情况下，分析了在不同工作频率时的横向波矢量间布里渊区色散特性，对空间谐波的相互作用情况也进行了研究。其次，在给定工作频率的情况下，分析了不同纵向波矢量和不同调制系数时的横向波矢量间布里渊区色散特性。由于空间谐波的相互作用随纵向波数或调制系数的增大而增强，导致阻带能明显地表现出来，从而使介质波导阵列的横向传播特性能较为全面地得到分析。     

The Amplitude of Longitudinal Characteristic Modes in Dielectric Waveguide Array

It's not adequate to just obtain eigenvalue for solving eigenvalue problem. Since the eigenvalues associated with longitudinal characteristic modes in dielectric waveguide array (DWA) has been studied, the paper concentrates on the corresponding eigenvector, namely, the amplitude of these characteristic modes. Through numerical study of the amplitude of longitudinal guided TE and TM modes in DWA, space harmonic (SH) coupling and energy conversion effect have been discovered. The paper not only contribute to deep understand the mechanism of SH interaction, but also do good to analyze the resonance, radiation problem in DWA.     

Investigation of Terahertz Wave Propagation Along Shielded Dielectric Multiple-Slot Waveguide

In this paper, a shielded dielectric multiple-slot waveguide is presented and demonstrated by theoretical calculation at terahertz frequencies. Some electromagnetic analysis of waveguide currently employed simplified intrinsic frequency dispersion models for the bulk conductivity of normal metals used in terahertz wave structures. This paper has compared various conductivity models for gold between 0.1-3 THz. The dielectric loss, conductor loss, total propagation loss with different conductivity models and E-field distribution has been obtained by numerically solving the complex eigenvalue equation for the propagation constant. The analysis results are in agreement with the assumption of R. Sun et al. and the experimental results obtained by H. Sun et al. The propagation loss deviation between various models is less than 3% at 0.2-0.5 THz. Comparisons with other slot waveguides are also given. The analysis results show that the proposed line has lower propagation attenuation than other slot waveguides.     

Ka-band Dielectric Waveguide Antenna Array for Millimeter Wave Active Imaging System

Ka-band compact dielectric waveguide antenna array for active imaging system is given. Antenna array with WR28 metal waveguide direct feeding is specially designed with small size, high gain, good radiation pattern, easy realization, low insertion loss and low mutual coupling. One practical antenna array for 3-D active imaging system is shown with theoretic analysis and experimental results. The mutual coupling of transmitting and receiving units is less than -30dB, the gain from 26.5GHz to 40GHz is (12-16) dB. The results in this paper provide guidelines for the designing of millimeter wave dielectric waveguide antenna array.     

Characteristic Electromagnetic Fields in Dielectric Waveguide Array

Based on the modal solution of one dimensionally periodic structure with piecewise uniform dielectric constant distribution, characteristic solutions for two dimensionally Dielectric Waveguide Array (DWA) are rigorously formulated. By satisfying periodic boundary conditions in the interfaces inside a unit cell, semi-closed-form dispersion relation for DWA can be established. Numerical results are presented and compared with a previous method. A class of guidance and radiation problems can be solved with much more simplicity and accuracy.     

Propagation in Dielectric Slab Loaded Rectangular Waveguide

Propagation in dielectric loaded rectangular waveguide is investigated theoretically for varying slab thickness and dielectric constant. The slabs are placed across the center of the waveguide in the E plane. This geometry is found to offer bandwidths in excess of double that of rectangular waveguide for dielectrics having dielectric constants of approximately 18. Power handling capacities which are double or triple that of standard waveguide are achievable using the dielectric loaded waveguide. In addition to the theory, design curves of bandwidth, guide wavelength, cutoff wavelength, impedance, power handling capacity, wall losses, and dielectric losses are presented and compared to experiment where possible.     

光子晶体线缺陷构成的波导中光的传输

对由光子晶体线缺陷构成三种形式的光波导,用有限差分法研究光波在其中的传播规 律,发现不同形状的波导能够导引不同频率的光波。低频光波易从直波导传输,而折线型波导频谱通带较窄,低频光波不能通过。研究结果为光子器件的设计提供了理论依据。     

Propagation in Rectangular Waveguide Containing Inhomogeneous, Anisotropic Dielectric

The Wentzel, Kramers and Brillouin (WKB) approximation is used to solve the wave equations for propagation of guided waves in rectangular waveguide containing an inhomogeneous dielectric. The simplest form of anisotropy is used to characterize the relative dielectric constant, i.e., it is assumed that the relative permittivity tensor is diagonalized with respect to the waveguide coordinants. Each of the elements of the relative permittivity tensor is allowed to vary continuously across the broad dimension of the waveguide. The TE/sub nm/ and TM/sub nm/ cases are analyzed for the instance of completely filled guide, while the TE/sub no/ modes are considered for slab-loaded guide.     

Wave Propagation in Sinusoidally Stratified Dielectric Media

The dispersion properties and the fields of electromagnetic waves are investigated for propagation in a stratified infinite medium. The stratification is characterized by a dielectric constant which, along one coordinate, is modulated sinusoidally about an average value. A systematic and comprehensive study is presented for the case of H modes for which the pertinent wave equation is in the form of a Mathieu differential equation. The modes and dispersion characteristics are analyzed in terms of a "stability" chart, which is customary in the study of the Mathieu equation. Results are obtained for an unbounded medium and for a waveguide filled with the modulated medium. Also, the reflection occurring at an interface between free space and a semi-infinite medium of this type is examined. In addition to these rigorous results for arbitrary values of modulation, simple analytical expressions are given for all of these cases where the modulation in the dielectric is small. It is shown that the fields are then expressible in terms of the fundamental and the two nearest space harmonics. The fields within a unit cell in the stratified medium are calculated for both small and large modulation and for frequencies up through the second pass band. It is of interest that the variation of the fields is not, in general, simply related to the variation of the dielectric constant within a cell.     

Propagation in Rectangular Waveguide Filled with Skew Uniaxial Dielectric

A solution is given for propagation in rectangular waveguide fully loaded with a uniaxial dielectric, with the C-axis lying anywhere in the transverse plane. This problem arises in the design of particular traveling-wave masers. By application of the Rayleigh-Ritz method to Berk's variational expression, the problem is reduced to a matrix eigenvalue problem, and in a form suitable for direct evaluation on a digital computer. An explicit approximate solution is, however, shown to give accurate results. The analysis can be interpreted directly in terms of mode coupling of the usual rectangular waveguide modes, and the possible extension is indicated to general tensor media and to circular or elliptical waveguide.     

矩形介质波导阵列的一种新型分析方法

本文将等效介电常数近似分析方法在应用范围和处理方法上进行了一些改进．发展为双等效介电常数近似分析法，然后用它来分析矩形介质波导阵列．推得两个一维周期的耦合特征方程。如果将Macatili方法应用范围扩展用来研究该波导阵列也会得到同样的结果，它们都能在二维平面上较准确地反应出通带和阻带等主要周期特性。     

Wave Propagation Along a Helical Step-Loaded Groove Waveguide

A new kind of helical groove structure, step-loaded groove waveguide is presented and analyzed in this paper. The dispersion equation of this structure is derived by means of a field-matching method. This equation may be reduced to the dispersion equation of helical ridge-loaded structure and rectangular one. In order to demonstrate the influence of the step on the dispersion properties, the comparison of the dispersion characteristics is made in these helical rectangular and modified rectangular groove structures. Form the analysis, it is shown that the step loading tends to reduce the dispersion of the helical groove circuit and the step-loaded structure has the weaker dispersion compared with the rectangular one or the ridge-loaded one. The effect of the step shape on the wave properties is also discussed under the deep groove case. The theoretical results explicitly indicate that the V-like step-loaded structure has the weakest dispersion in all step-loaded structures.     

Mode Propagation through a Step Discontinuity in Dielectric Planar Waveguide

This paper presents two methods for dealing with wave propagation through a dielectric step discontinuity at normal incidence. One method helps to accelerate the convergence of solutions, especially for the TM-mode problem, and the other treats efficiently the continuous mode spectrum by introducing the Legendre transform in the case of open waveguides. As for the former, the singular fields around the dielectric edges are introduced in terms of direct use of their functional forms to the boundary condition, which is fulfilled in the sense of least squares. As for the latter, the expansion in terms of the Legendre functions is performed for optimally divided ranges of a continuous spectrum. A number of numerical examples prove that the methods presented herein are quite powerful for solving the TM-mode discontinuity problems in dielectric waveguides of both closed and open types.     

Propagation in a Waveguide Partially Filled with Anisotropic Dielectric Material

A rectangular waveguide partially filled with an anisotropic dielectric material has been studied. The method of analysis has been shown to be quite powerful. A new configuration with a rectangular waveguide unsymmetrically loaded with a rectangular dielectric insert has been analyzed, tested experimentally. The special effects of mode coupling by breaking the symmetry of the structure are studied and the consequences for single-mode operation with application to masers in the millimeter-wave region are demonstrated.     

Magnetostatic Wave Propagation in a Finite YIG-Loaded Rectangular Waveguide

The propagation of magnetostatic waves (MSW) in a waveguide partially loaded with a low-loss ferrite slab is investigated theoretically. The most common low-loss ferrite material used for MSW propagation is epitaxial yttrium iron garnet (YIG). A YIG slab is placed inside and along the guide and not in contact with the sidewalls of the wavegnide. The dc magnetic field is assumed to be parallel to the YIG slab and perpendicular to the direction of propagation. Using the integral equation method, the dispersion relation is found to be an infinitely large determinant equal to zero. Proper truncation of this determinant and numerical analysis to find its roots are carried out in this work. It is seen that in order to obtain high values of group time delay, the YIG slab must be narrow and placed at the bottom of the guide. On the other hand, to maximize the device bandwidth, a narrow YIG slab positioned at the top inside surface of the waveguide is preferred. It is also noticed that there exists a tradeoff between the time delay and the device bandwidth and that maximization of one property leads to a poor value in the other. Thus, some design compromises should be made. It is also observed that the frequency range of operation of the device can be adjusted by an external magnetic bias field. This property of tuning the device to operate in any frequency range adds an extra dimension of flexibility to the operation and also to the design of these devices.