Conductive contacting spheres on the centre of the broad wall of rectangular waveguides

It has been found that metallic balls (held by external magnets) in rectangular waveguides produce a frequency-independent reflection, and an empirical formula is given for the magnitude of the reflection coefficient.     

Full-wave analysis of dielectric waveguides using tangential vectorfinite elements

A novel method is presented for the analysis of dielectric waveguides. This method provides four major new contributions: (1) a transformation of variables is introduced that allows propagation constants to be computed directly; (2) H₁ (curl) tangential vector finite elements are applied to dielectric waveguides to obtain reliable approximate electromagnetic fields; (3) the Lanczos algorithm is modified to solve the required eigenmatrix equation efficiently; and (4) the reaction principle is used to provide a posteriori error estimates for use in adaptive mesh refinement. The method produces reliable solutions and applies to structures that contain both electric and magnetic inhomogeneities. The answers are refined adaptively to generate waveguide eigenmodes to a specified accuracy. Numerical results of an image guide, a microstrip transmission line, and a pedestal-supported stripline are shown. Computed solutions agree very well with previously published results     

Full-wave analysis of coplanar waveguides by variational conformalmapping technique

A new full-wave analysis of coplanar waveguides is presented. The modified mapping technique of C.P. Wen (1969) is used to map the original infinite domain into a finite image domain and also to account for the singularity of fields near the conductor edges. The finite thickness of the dielectric substrate is considered together with the assumptions of lossless guides and negligible metallization thickness. The current distributions on the center signal strip as well as the tangential electric fields over the slot along the air-dielectric interface are examined. Numerical results for the frequency-dependent effective dielectric constants and characteristic impedances of coplanar waveguides are presented. Particular attention is given to the electric field distributions over the air-dielectric interface of slots and the current distributions of the signal strip     

Coupling by slots in rectangular waveguides with arbitrary wall thickness

A method for evaluating the coupling between two rectangular waveguides, coupled by a slot of arbitrary dimensions in a wall of arbitrary thickness is described. The method is based on the solution, by numerical techniques, of a pair of coupled integral equations. Results for typical shunt and series slots are presented.     

Narrow wall axial-slot-coupled T junction between rectangular andcircular waveguides

An analysis is presented of a T junction between rectangular and circular waveguides coupled through a long axial slot in the narrow wall of the rectangular waveguide. A moment method with entire orthogonal basis functions is used for deriving expressions for the elements of the scattering matrix. The effect of the wall thickness is taken into account by treating the coupling slot as a short section of a rectangular waveguide and matching the boundary conditions at the interfaces. The conditions satisfied by the scattering matrix of the junction are verified. A comparison between theoretical and experimental results on variation of coupling with frequency is presented     

Characteristics of TE-modes in rectangular waveguides containing dielectric layers

The eigenequation of TE-modes in rectangular waveguides filled with arbitrary layer dielectrics is presented. As an example, we calculate the characteristics of a rectangular waveguide which is devided three regions by dielectrics. Using a Personal Computer the results can be got in several minutes, and the results agree with that of other authors very well. Some curves are given.     

Full-wave analysis for antennas with mixture structure of planarelements and waveguides

Interest in planar antennas for small satellite communication earth terminals is growing rapidly. A planar element-waveguide mixture structure antenna is analyzed using a spectral domain approach and eigenfunction technique. The difficulty in satisfying the boundary conditions on the side walls of cavities and waveguides in the spectral domain is overcome. The confidence in our method is strengthened further by the convergence of the mode series and the fine agreement between the theoretical and experimental results     

Compound radiating slots in a broad wall of a rectangular waveguide

An analysis is presented of the characteristics of a broad wall radiating slot, offset from the center line and tilted with respect to the longitudinal axis of a rectangular waveguide. Pertinent integral equations are developed, taking into account finite wall thickness, and are solved for the slot aperture E-field using the method of moments. Compound slot characteristics are then deduced, including resonant length and dominant mode scattering. Numerical results for the scattering from resonant slots are presented over a range of offsets, tilt angles, frequencies and waveguide dimensions. For resonant compound slots, offset and tilt are shown to control the aperture electric-field amplitude with a phase variability of 360°. The results have significant applications in the design of compound slot arrays     

Rigorous analysis of printed windows in rectangular waveguides

The printed windows in rectangular waveguides have been investigated using a combined method of modal analysis and generalised scattering matrix for the first time. The method takes into account the influences of the nonzero metallisation thickness and the mounting grooves. The frequency characteristics of the unilateral and bilateral windows are illustrated.<>     

Eigenwaves of periodic rectangular waveguide with dielectric-filled dips on broad wall

The paper presents a solution of the boundary problem for eigenwaves of periodic structure consisting of rectangular waveguide with dielectric-filled dips on broad wall obtained by Galerkin’s method. The types of waves are analyzed with due regard for the symmetry of structure and field. The results of calculations of basic characteristics of eigenwaves in the baseband are also presented.     

Form of field in small-offset longitudinal slot in broad wall of rectangular waveguide

A surface-patch moment method approach is used to examine the electric field distribution in longitudinal slots that have small offsets from the host rectangular waveguide centreline. It is shown that the phase of the transverse electric field in the slot may display a large variation across the slot narrow dimension in such instances.<>     

Numerical analysis of centered-inclined coupling slots in rectangular waveguides

Numerical analysis is presented for the characteristic parameters of centered-inclined coupling slot in rectangular waveguides,taking into account the transverse distribution of the electric field across the slot aperture.Integral equations are formulated based on dyadic Green＇s function theories and solved using the method of moments.Trigonometric basis functions are adopted.It is found that the method will converge with up to ten basis functions.The characteristic parameters can be easily obtained for different slot sizes.Resonant length and resonant resistance of the coupling slots are calculated.It is shown that the calculated results have very high accuracy,compared with simulated results obtained from commercial software.Therefore,it can be effectively applied in the synthesis of antenna arrays.Effects of the transverse distribution on calculating resonant parameters of the coupling slot are also analyzed.The results show that if the transverse distribution of the electric field is neglected,the calculated error tends to become larger when the slot gets wider or thinner.     

SCATTERING ANALYSIS OF E-PLANE UNIFORM DIELECTRIC POSTS IN RECTANGULAR WAVEGUIDES

Based on the polarization current integral equation with the modified Green's Function as ker-nel, the scattering properties of the E-plane. uniform dielectric posts in rectangular waveguide arenumerically analyzed by the moment method. These posts are of arbitrary cross section and post-numberThe calculation accuracy and speed are remarkable improved by segmenting the dielectric region into manysmall rectangular oells and applying local analytic integration. The higher-order modes are considered in cal-culation, improving the computation accuracy and providing the scattering information of all modes excitedas well.     

Full-wave analysis of discontinuities in planar waveguides by themethod of lines using a source approach

An accurate full-wave analysis of discontinuities in shielded microwave structures by the method of lines is presented for use in microwave integrated circuit design. The input currents are derived from a sinusoidal source representation and modeled by inhomogeneous boundary conditions. Interacting discontinuities can be treated without segmentation. Inhomogeneous boundary conditions are introduced to account for the excitation. Analysis shows that in discretizing the differential operators additional source terms which result in inhomogeneous differential equations are obtained. A deterministic equation for the current distribution is derived. For higher flexibility, nonequidistant discretization is used. The scattering parameters are presented for the microstrip step discontinuity and for a single-filter structure with interacting discontinuities, namely a coupled line filter. The filter characteristics are compared with measurements. Measurements verify the filter calculations     

Characteristics of a longitudinal/transverse coupling slot incrossed rectangular waveguides

A rigorous analysis of a broad-wall slot coupler between two crossed rectangular waveguides is presented. The slot is longitudinal and offset from the center line in the main guide and is centered transverse in the branch guide. Integral equations are developed, taking into account finite wall thickness. The integral equations are then solved for the aperture electric field. Coupling slot characteristics are obtained, including the resonant length and dominant mode scattering. Numerical results for resonant length and scattering parameters are presented over a range of offsets, waveguide dimensions, and frequencies     

Analysis of longitudinal slots in rectangular waveguides

An accurate computation of the admittance characteristics of longitudinal shunt slots in a rectangular waveguide is presented. A moment method with entire basis functions is used for solving the electric field in the slot. The waveguide wall thickness is accounted for by introducing higher order waveguide modes in the short waveguide connecting the inner and outer regions. Particular attention is given to the resonant length of the slot, which is a critical parameter in the design of waveguide slot array antennas. Computed resonant lengths compare very well with measured results.     

Determination of bending losses in rectangular waveguides

This paper details an accurate method for computation of bending losses in rectangular optical waveguides which we combine with perturbation theory to account for the fields in the (outer) corner regions of the guiding channel. In the case of the weakly guiding channels of interest in optical signal processing, the correction to the loss coefficient due to the corner fields is shown to be in excess of 50%     

Full-wave CAD of a rectangular waveguide filter with integratedcoaxial excitation

Coaxial waveguides are very commonly used in many microwave subsystems for the connection of various components. Significant size reduction could, therefore, be achieved by integrating the design of the coaxial transition in the computer-aided design (CAD) of microwave filters. In this context, we first discuss in this paper a coaxial transition, which can be efficiently designed interactively using an accurate and efficient CAD procedure. The key elements of the CAD tool developed are then described and a specific example of a microwave filter is discussed. In addition to theory, measured results are also presented, thereby fully validating both the CAD tool and the structures proposed     

Numerical analysis of open rectangular and similar ɛ-gyrotropic semiconductor waveguides

In the paper, electrodynamic parameters of open longitudinally magnetized n-InSb waveguides have been analysed by means of singular integral equations. Waveguide's cross — section shapes are made of rectangles. Dispersion characteristics certainly depend on the shapes and may be essentially different. Particularly one waveguide has high frequency cut-off of the first higher mode in the band under consideration. Dependence of propagation constant on carrier concentration is nonlinear for every computed waveguide.     

Near-zone gain of open-ended rectangular waveguides

Full-wave solutions to the problem of radiation by open-ended rectangular waveguides (OEG) are presented. The radiation problem is formulated in terms of an electric field integral equation (EFIE). The EFIE is solved using the method of moments for three OEG antennas covering the frequency range from 200 to 750 MHz. Results for the near-zone gains as a function of both frequency and distance from the OEG aperture are presented. Estimates for uncertainties in the calculated gain are also given