E-plane cross junction loaded with central metallic post

The Least-Squares Boundary Residual Method is utilized in the present paper for the analysis of the E-plane cross junction that has a centrally located metallic post. The computer model thus developed (which is able to yield numerical accuracies of ±0.5%) has thereafter been used to design a prototype that has the same electrical characteristics over the 26–40 GHz bandwidth as the H-plane cross junction reported earlier by Suet al in [1].     

Symmetrical N-port waveguide junction loaded with dielectric sleeveand metallic post

The present paper describes the development of a computer model that is able to predict the characteristics of the symmetrical N-port waveguide junction, which has a dielectric sleeve and metallic post inserted concentrically into its central cavity. Computational and experimental test results demonstrate that the resultant software package (which is compact enough to be run on an IBM 486 PC) can yield accuracies of ±0.5% for the scattering parameters of the junction     

An analysis of a waveguide T junction with an inductive post

The authors analyze the T junction with an inductive post, taking its diameter into account for the case where the current distribution is assumed on the surface of the post. A single cylindrical post placed in a T junction improves the impedance matching and compensates the junction discontinuity in a wide frequency band. The effects of the design parameters, such as the diameter of the post and its location, are clarified. The measured return loss is accurately predicted. On the basis of this analysis, an effective design procedure for the T junction is proposed, and the reflection below -30 dB is realized over 4% bandwidth     

Scattering from parallel metallic cylinders with arbitrary cross sections

The integral equations for scattering by a set of parallel metallic cylinders, each cylinder of arbitrary cross section, are solved directly by means of a digital computer program giving the current distribution induced on the scatterer surfaces, the scattering cross section vs azimuthal angle, and the induced field ratio (IFR) for both parallel and perpendicularly polarized incident waves. The present program is suitable for cylinders up to25lambdato40lambdacircumference. The validity of the computer program has been verified by comparing results 1) with exact calculations for circular cylinders, 2) with measured values for more than 40 rectangles and rectangles with feathered and rounded faces, and 3) by interchanging the direction of incidence and the direction of observation, whereby, according to the reciprocity theorem, the observed scattered field must remain the same.     

Scattering from a circular dielectric post embedded in a groundeddielectric sheet waveguide

A systematic method for obtaining the scattered electric field in a grounded dielectric sheet waveguide is presented. It is shown that the point-matching method can be used for an explicit calculation of the integral equation to estimate the scattering from a circular dielectric post embedded in the grounded sheet. The magnitude of the reflection coefficient as a function of dielectric constant is given     

Scattering from dielectric cylindrical shell periodically loaded with metallic patches

A dielectric cylindrical shell that is covered with metallic patches is considered. Entire domain basis functions are employed in the moment method solutions and the infinite sums are accelerated by Kummer's method. Results show that the radar cross-section of the structure vanishes at some specific frequencies.     

Scattering by the transition junction between a conventional and a high-temperature superconducting waveguide

TE10 mode scattering during the transition from a conventional to a superconducting rectangular waveguide is investigated based on the Meissner model. The reflection coefficient, input impedance and equivalent inductance are calculated in cm-wave bands when the TE₁₀ mode is incident on the discontinuity from the conventional (or non-superconducting) waveguide.     

A rigorous analysis of a cross waveguide to large circularwaveguide junction and its application in waveguide filter design

A rigorous analysis is obtained for the problem of scattering at the junction of a cross-shaped waveguide and a larger circular waveguide. The general case of an arbitrary offset and orientation of the cross waveguide axes is considered. The fields matching over the cross aperture of the smaller guide is facilitated by using the transformation of the circular cylindrical Bessel-Fourier modal fields of the circular guide into a finite series of exponential plane wave functions. This permits an analytical finite series solution for the elements of the fields mode matching matrix, from which the general scattering matrix of the junction is obtained. The application of the formulation to circular waveguide filter design is emphasized in the numerical examples. Excellent agreements between theoretical and experimental results are obtained in all the numerical examples     

Scattering from a cylindrical waveguide with rectangularcorrugations

Electromagnetic scattering from a circular cylindrical waveguide with rectangular corrugations is considered in this paper. An analysis method based on dyadic Green's functions and Fourier transforms is used to get the field in terms of modal currents induced on the corrugation openings. The fields are expressed through a series of modal eigenfunctions in the corrugations, and are integrated to get the unknown expansion coefficients. This analysis method can easily be extended to find the dispersion relations of the corrugated waveguide. The series solution obtained is analytic and suitable for numerical computation. Numerical results are presented to illustrate the scattering behavior of a corrugated cylindrical waveguide in terms of frequency and waveguide geometry     

Field distribution in a waveguide loaded with a thin slab of InSb

Nonreciprocal microwave properties at F band and W band have been observed at room temperature in waveguides loaded with thin slabs of n-InSb. Measurements have shown that the nonreciprocal properties previously observed at K band are indeed maintained from the microwave to the millimeter wave region as previously predicted.     

Scattering loss in a cladded-fibre optical waveguide

An exact analysis using the Green's-function formulation of the problem of scattering from a local inhomogeneity inside a cladded-fibre waveguide is carried out, and yields a radiation loss higher than that evaluated from the infinite-medium approximation.     

COUPLING PROPERTIES OF THE SLOT IN A WAVEGUIDE JUNCTION

The coupling properties of a transverse slot in the common wall between two buttingrectangular waveguides are discussed.By means of Galerkin's method which takes into accountthe wall thickness,equivalent magnetic currents on the aperture surface of the slot are obtained,and then the general formulae of scattering fields and of equivalent parameters are derived.Thedimensions as well as seats of those two waveguides and the slot,and the thickness of the wall arearbitrary.For example,the transforming coefficients and the VSWRs of numerical calculationand experimental results are given.They are in good agreement.     

Scattering by thin wire loaded with a ferrite ring

A coupled integral equation formulation and a method of moments (MoM) solution are presented for the problem of scattering by a thin conducting wire of circular cross section with ferrite loading. It is proved that ferrite loading can be used to reduce the radar cross section of long thin objects at their resonant frequency     

Scattering at a nonchiral-chiral interface in a coaxial waveguide

A formally exact full-wave solution is presented for the problem of scattering at a nonchiral-chiral interface in a coaxial waveguide. The field components for the axisymmetric modes in a coaxial chirowaveguide are initially obtained. A new orthogonality relation for the modes is then proposed and used to find expansion coefficients for the electromagnetic fields in the coaxial chirowaveguide. The scattering matrix for the nonchiral-chiral dielectric discontinuity in a coaxial waveguide is finally derived by enforcing the continuity conditions of the tangential field components across the interface. Numerical results for the reflection and transmission coefficients at the nonchiral-chiral interface in a coaxial waveguide are presented     

Scattering by a dielectric obstacle in a rectangular waveguide

A method for the computation of S-parameters associated with a rectangular waveguide with a rectangular or cylindrical obstacle of arbitrary complex scalar permittivity is presented. The method uses modal analysis and integral relationships to connect appropriate components of the field. In this way, convergence is achieved faster than by point-matching techniques. Our method is well adapted to resonance problems, as illustrated by comparison with both theoretical and experimental results     

Aperture matching of a dielectric loaded circular waveguide elementarray

An X-band phased array with dielectric-loaded circular waveguide elements was investigated. The aperture was designed to provide balanced scan characteristics for both the E- and H-planes. The results of an experimental study are presented in which the active impedance of the radiating element was matched by introducing a circumferential groove onto the dielectric plug. Both the aperture junction and the matching groove were measured to derive their respective equivalent circuits for `look-in' and `look-out' impedance transformations. The groove size and its location from the aperture were then optimized by a hybrid approach wherein the measured data and computer simulations were used to greatly reduce the shop time, lab tests, and the number of trials in the hardware development     

Analysis of a modified variable-length tuning post in a rectangular waveguide.

A modified variable-length post for use in high power waveguide tuning networks is analyzed to determine its reactance properties. Theoretical predictions are shown to be in good agreement with experimental results. An investigation of the reactance characteristics and the aperture voltage characteristics of the modified post, as a function of its dimensions, is also reported.     

Scattering at an offset circular hole in a rectangular waveguide

A solution is given for the problem of scattering at an offset circular to rectangular junction and at a thick diaphragm, with an offset circular aperture, in a rectangular waveguide. The method used is mode matching for computing one discontinuity. The difficulty arising from the fact that the eigenmodes of the two waveguides are known in different coordinate systems is overcome by simple transformation for the evaluation of overlap integral between the eigenmodes of each waveguide. Experimental results validate this method     

Electromagnetic radiation control in metallic waveguide with gyrotropic semiconductor wall

New possibilities of using magnetoplasma effects in semiconductors for the millimeter radiation control are discussed. For this purpose a highly-conductive semiconductor plate has been substituted for a part of the wide wall of metallic rectangular waveguide and the external magnetic field has been directed perpendicularly to the plate surface. It is shown that this construction can be used both as a second — harmonics filter and a directional coupler.