Analysis of Radiation Phenomena in a Wedge Ended Dielectric Slab Waveguide

Radiation phenomena observed in a wedge shape ended dielectric slab waveguide are analyzed using mode matching technique. The case of transverse electric polarization (TE) being parallel to dielectric slab waveguide is assumed. In order to describe the fields in the wedge region, a stack of dielectric plates is assumed and in each layer the fields are expanded in terms of the mixed spectrum of guided and radiated modes. A similar expansion is used in the constant thickness slab waveguide while in free space medium a continuous-radiation mode expansion is used. Then a mode matching approach is applied, incorporating the orthogonality properties of mixed spectrum modes, in order to compute the wave fields inside the dielectric slab waveguide and wedge medium. Mode matching is achieved by discretizing the continuous radiation mode spectrum leading into a numerically stable solution provided a sufficient large number of points are used to convert integrals into finite summations. Numerical computations are carried out for various wedge geometries and shapes including linear and exponential profiles.     

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.     

Dielectric Losses in an H-Plane-Loaded Rectangular Waveguide (Short Papers)

The attenuation constant due to dielectric losses in a rectangular waveguide loaded with a dielectric slab in the H-plane is calculated. Results for the dominant LSM/sub 11/ mode are presented graphically.     

介质片非对称加载矩形波导中的TEM场区

本文证明了具有不同介电常数和厚度的双片介质加载矩形波导中可以存在TEM场区,并导出了介质片厚度与介电常数和工作频率之间应满足的关系,讨论了这种波导的传输特性。     

Analysis of radiating slots in a rectangular waveguideinhomogeneously loaded with a dielectric slab

Longitudinal and transverse radiating slots in the broad wall of a rectangular waveguide inhomogeneously loaded with a dielectric slab are analyzed. The formulation used involves the moment method solution of a pair of coupled integral equations containing the dyadic Green's function of the inhomogeneously loaded waveguide. Both an edge-condition for the electric field in the slot aperture and the correct form of the ψ=constant waveguide mode are included in the analysis. Computed and measured results are compared to verify the theoretical analysis     

Some Effects of Dielectric Loading on Ferrite Phase Shifters in Rectangular Waveguide

The use of dielectric loading with the ferrites in nonreciprocal transmission lines has becolme quite prevalent. The theoretical analysis of unloaded ferrite phase shifters in rectangular waveguide has been extended to the dielectrically loaded case by Soohoo. The boundary-value problem of ferrite phase shifters in dielectrically loaded coaxial lines, which possesses a transcendental equation similar to the waveguide case, has been throughly discussed by several authors. The present commumcation reports the solution of the boundary-value problem of a dielectrically loaded ferrite phase shifter in rectangular waveguide to yield values of the lossless propagation constant for various slab positions for both directions of propagation. The theoretical values of the differential phase shift for slab positions about the center of the waveguide were compared with the measured values for three different applied magnetic fields.     

A new approach to estimate complex permittivity of dielectricmaterials at microwave frequencies using waveguide measurements

In this paper, a simple waveguide measurement technique is presented to determine the complex dielectric constant of a dielectric material. The dielectric sample is loaded in a short-circuited rectangular waveguide. Using a network analyzer, the reflection coefficient of the waveguide is measured. Using the finite-element method (FEM) the exact reflection coefficient of this configuration is determined as a function of the dielectric constant. The measured and calculated values of the reflection coefficient are then matched using the Newton-Raphson method to estimate the dielectric constant of a material. A comparison of estimated values of the dielectric constant obtained from simple waveguide modal theory and the FEM approach is presented. Numerical results for dielectric constants of Teflon and Plexiglas measured at the X- and Ku-bands are presented. Numerical inaccuracies in the estimate of the dielectric constant due to: 1) the presence of airgaps between sample and sample holder waveguide surfaces and 2) inaccuracy in the sample dimensions are also discussed     

Broad-Band Quarter-Wave Plates

Analytical expressions are given for the propagation constant for the two orthogonal dominant modes in a square waveguide loaded with a centered slab of dielectric. These are combined to find the differential phase shift in a loaded section. Solutions of these equations are given for polystyrene which enables one to design broad-band quarter wave plates. The problem of transforming from unloaded to loaded guide is discussed and two solutions are given and another suggested. Experimental results are given and it is found that the work in square guide carries over to circular guide almost intact. It is shown that quarter-wave plates may easily be designed to cover a normal waveguide bandwidth.     

Application of a Variation-Iteration Method to Waveguides with Inhomogeneous Lossy Loads

An approximate technique for solving eigenvalue equations, the variation-iteration method,is commonly used in theoretics physics. A previous paper presented the application of this method to the scalar case of a dielectric slab loaded rectangular waveguide. This paper presents its extension to the complex vector case of a lossy dielectric insert loaded waveguide. Starting from an initial trial function, iterates are calculated in which the components relative to the unwanted eigenfunctions are eliminated. Both an upper and a lower bound for the unknown eigenvalues are available. Each iterate is the solution of a system of algebraic simultaneous equations. This system is solved by the successive overrelaxation method using an automatically computed optimal accelerating factor. An extrapolation technique further accelerates the convergence. This yields the attenuation and propagation coefficients for the dominant as well as several other modes, together with the electric and magnetic field configurations.     

Propagation of soliton waves in nonlinear dielectric slab waveguides of parabolic index of refraction

The pulse propagation in a non-linear slab waveguide of parabolic index of refraction is treated by using differential equation techniques. A graded index dielectric slab waveguide free of material dispersion with a cubic order non-linearity is considered. The electromagnetic wave inside the waveguide is described in terms of a non-linear equation. Slowly varying envelope function representation is employed to develop a non-linear partial differential equation for the unknown envelope function of the electric field. An averaging method over the transverse direction is applied to reduce the unknown envelope function non-linear differential equation into a form resembling the well known non-linear Schrödinger differential equation. This equation is solved by applying the Inverse Scattering Method. The N-soliton solution is developed and presented explicitly for the practical case of the single mode dielectric slab waveguide. Numerical results presenting single and double soliton propagation are also given.     

A multipole analysis of a dielectric loaded coaxial rectangularwaveguide

A multipole analysis of a coaxial rectangular waveguide whose inner conductor is circular is made in order to determine the TE and TM modes of the system. The analysis is based on using multipole (dipole, quadrupole etc.) electric and magnetic current sources to generate field solutions in the waveguide. These solutions are used to match the electromagnetic boundary condition in a homogeneous coaxial rectangular waveguide and to determine the TE and TM eigenvalues of the waveguide system. Eigenvalue results are compared with results of the generalized spectral domain method and to eigenvalue results for a ridged waveguide. Propagation in a coaxial rectangular waveguide is also studied when the coaxial rectangular waveguide is loaded with lossy inhomogeneous dielectric material. A variational formula is used to relate the TEM, TE, and TM modes of an empty coaxial rectangular waveguide to the propagation in the loaded inhomogeneous dielectric waveguide     

Radiation Characteristics of a Dielectric Slab Waveguide Periodically Loaded with Thick Metal Strips

A theoretical analysis is presented for the radiation characteristics of a dielectric slab waveguide periodically loaded with thick metal strips. A boundary-integral-equation formulation is employed to describe the fieIds in the grating layer. Through numerical calculations, we show that the leakage constant of the fundamental TM mode is much larger than that of the fundamental TE mode. This property will find application in mode filters for millimeter- and submillimeter-wave integrated circuits.     

Numerical analysis of H-plane waveguide junctions bycombination of finite and boundary elements

A numerical method is formulated for the analysis of H-plane waveguide junctions with arbitrary cross sections. The junctions are loaded with arbitrarily shaped dielectric or ferrite. The method is a combination of the finite-element method and the boundary-element method, and is applied to the regions with and without dielectric or ferrite, respectively. To show the validity and usefulness of the method, a lossy dielectric post and a ferrite slab in a rectangular waveguide are investigated in detail, and the computed results are compared with earlier theoretical and experimental results     

旋磁介质加载矩形波导中TEM场的研究

本文首次得出了矩形波导中进行旋磁介质加载可以存在均匀 TEM 场区的特性,导出了在两种不同的磁化状态下传播常数所满足的特征方程以及存在 TEM场区时旋磁介质的尺寸、材料参数和频率之间的关系,并对一些有关的特性进行了分析和研究。     

Discontinuities in a Rectangular Waveguide Partially Filled with Dielectric

The modal spectrum for a rectangular waveguide with a dielectric slab at the bottom of the guide is obtained following the Characteristic Green's Function method developed by Marcuvitz. Then a four-terminal network is found as equivalent to the junction of the partially filled waveguide and an empty rectangular waveguide. An integral equation is written for the electric field at the plane of the junction and variational expressions are derived for the parameters of the four-terminal network connecting the transmission line equivalent to the partially filled waveguide to the transmission line equivalent to the empty guide. A reasonable guess for the electric field at the discontinuity gives approximate values for the parameters of the four-terminal network. These values agree with experiment. The parameters of the network are plotted vs frequency and thickness of the slab.     

Approximate cutoff frequency of dielectric ridge waveguide, with application to travelling-wave masers

An approximate relation is obtained between the cutoff frequency and the geometry for dielectric ridge waveguide. This relation suggests that the cutoff frequency of rutile slab loaded rectangular waveguide will be substantially raised if the slab height does not exactly equal the waveguide height.     

An Approximate Analysis of Dielectric-Ridge Loaded Waveguide (Short Papers)

The dielectric-ridge loaded waveguide is analyzed approximately in terms of coupled empty waveguide modes. Using this technique the propagation constant can be easily computed, thus allowing the prediction of the properties of a type of dielectric phase shifter. Experimental evidence is presented which indicates that a two-mode approximation yields reasonable accuracy if the dielectric ridge is on center, is relatively thin compared to the width of the waveguide, and has a low dielectric constant relative to that of free space /spl epsiv//sub 0/.     

Tube-contacted slab waveguide for millimetre and submillimetre waves

A new type of dielectric waveguide, which we call a tube-contacted slab waveguide, is proposed for millimetre and sub-millimetre waves. Transverse sizes of the waveguide can be made much larger than the wavelength. Dispersion characteristics and field distributions of the guided modes are calculated using the method of effective dielectric constant.     

Polarization rotation in periodic loaded rib waveguides

Polarization rotation in an asymmetric periodic loaded rib waveguide is analyzed by a scalar coupled-mode theory with vector correction. The scalar modes of the dielectric loaded rib waveguide are calculated by using a simple variational method. The polarization rotation is found to be caused by a geometric effect due to the asymmetric loading of the waveguide. By phase-matching the two polarized modes through the periodic loading, complete polarization rotation can be achieved     

有耗介质导波结构的高次杂交四边形边缘元分析

本文提出了一种高次杂交四边形边缘元方法。讨论了这种高次杂交边缘元的有限元空间构造，给出了其形函数的显形表达式。这种方法不仅消除了伪解而且能直接求解传播常数，从而无需迭代便能分析有耗介质导波结构的传输特性。对矩形导和条形介质填充波导本征模传播常数的计算表明这种高次杂交边缘元的计算精度比低次杂交边缘元要高出一个量级。