Transverse scattering matrix formulation for a class of waveguideeigenvalue problems

Based on the mode-matching procedure, a unified transverse scattering matrix formulation is presented for the characterization of a class of waveguide eigenvalue problems, which include not only closed but also open structures. As examples, calculations are carried out on the dispersion characteristics of ridged waveguides and their variations, nonradiative dielectric (NRD) waveguides, groove guides, microstrip lines, finlines and coplanar waveguides. Comparisons with published data are made and verify the versatility and accuracy of the method. Besides its generality, this approach is also superior to some other techniques in simplicity and numerical efficiency     

Numerical analysis and validation of the combined field surfaceintegral equations for electromagnetic scattering by arbitrary shapedtwo-dimensional anisotropic objects

The numerical solution of coupled integral equations for arbitrarily shaped two-dimensional, homogeneous anisotropic scatterers is presented. The combined theoretical and numerical approach utilized in the solution of the integral equations is based on the combined field formulation and is specialized to both transverse electric (TE) and transverse magnetic (TM) polarizations. As opposed to the currently available methods for anisotropic scatterers, the present approach involves integration over the surface of the scatterer in order to determine the unknown surface electric and magnetic current distributions. The solution is facilitated by developing a numerical approach employing the method of moments. The various difficulties involved in the numerical effort are pointed out, and ways of overcoming them are discussed in detail. The results obtained for two canonical anisotropic structures, namely, a circular cylinder and a square cylinder, are given and validated by results obtained by alternative methods     

Equivalent network approach for guided electron waves obliquelyincident on step discontinuities in planar heterostructures

An equivalent network approach is developed for the analysis of the guided electron wave obliquely incident on step discontinuities in planar heterostructures. Stress is placed on network representations to establish physical pictures of the quantum effects and to yield insight; in addition, a systematic: microwave network approach is employed. A coordinate transformation translates an “eigencoordinate mode” of the guided electron wave propagating at an angle to the step discontinuity into a “structure coordinate mode” propagating normally to the step discontinuity, so that the step can be viewed as a transverse discontinuity and a procedure for the normal incidence can directly be exploited; transmission line equations in the direction normal to the step discontinuity, the mode-matching procedure for the boundary-value problem, and an equivalent network for the guided electron wave obliquely incident on the step discontinuities can be obtained. Using this network, the input admittance formulation is carried out, with which one can easily derive the equations that estimate the scattering and waveguiding characteristics of the guided electron wave obliquely incident on step discontinuities. Numerical examples are presented for a three-layered electron waveguide with a stub, and it is shown that this structure operates as a channel waveguide in addition to an angle filter     

Propagation Constant of a Rectangular Waveguides Completely Full of Ferrite Magnetized Longitudinally

This paper is an analysis of rectangular waveguide completely full of ferrite magnetized longitudinally. The analysis is based on the formulation of the transverse operator method (TOM), followed by the application of the Galerkin method. We obtain an eigenvalue equation system. The propagation constant of some homogenous and anisotropic waveguide structures with ferrite has been obtained. The results presented here show that the transverse operator formulation is not only an elegant theoretical form, but also a powerful and efficient analysis method, it is useful to solve a number of the propagation problems in electromagnetic. One advantage of this method is that it presents a fast convergence. Numerical examples are given for different cases and compared with the published results. A good agreement is obtained.     

Currents on generalized Yagi structures

Characteristics of currents produced on an infinite linear array of parasitic radiators when one of the radiators is excited are found. Yagi antennas use arrays of electric dipoles; detailed analyses and results are given for a generalized Yagi structure in which the dipoles are inclined at an arbitrary, angle to the array axis. These results suggest a simple mechanical means for broadbanding. Calculations are carried out within a network formulation. The integral solution obtained from this formulation is used to demonstrate the interrelation between the properties of the array of radiators excited parasitically or excited as a phased array. The solution simplifies remarkably when the angle of inclination of the dipoles is54.74deg. The surface-wave components and the (feed) correction currents are then explicitly evaluated. Although for conventional Yagi structures surface-wave solutions have been found only for capacitive dipoles, for sufficiently small angles of inclination surface waves can exist on arrays of inductive dipoles.     

Novel Microwave Network for the Leaky-Wave Analysis of Evanescent Fields in Stub-Loaded Structures

In this paper, a new transverse equivalent network for the modal analysis of stub-loaded leaky-wave antennas is developed. The derived network is useful for the study of the radiation of evanescent fields that occurs when they reach the top aperture of the parallel-plate stub. This transverse network is based, for the first time, on a nonhybrid formulation of the constituent parallel-plates modes of order 1 (TE₁ ^Z and TE₁ ^Z ). The obtained network is an alternative to the one based on hybrid TE₁ ^Vand TE₁ ^V modes, and leads to a simpler transverse resonance equation. The new equivalent network is validated by obtaining leaky-mode dispersion curves for a previously studied leaky-wave antenna in non- radiative dielectric guide technology.     

Analysis of the electromagnetic scattering by thick gratings usinga combined FEM/MM solution

The problem of diffraction by a thick, conducting grating situated in an inhomogeneous dielectric slab is investigated using the generalized network formulation. This formulation combines the method of moments and the finite-element method, permitting the treatment of periodic elements of arbitrary cross section and inhomogeneous profiles. Solutions are presented for both transverse electric (TE) and transverse magnetic (TM) polarizations. Transmission gratings composed of rectangular conductors filled with dielectric materials of arbitrary profiles are studied     

Scattering from a double-strip grating: rigorous equivalent networkformulation

An exact solution for the problem of transverse electric (TE) or transverse magnetic (TM) plane-wave scattering from a periodic, planar double-strip grating at a dielectric interface is described. The metal-strip grating is assumed to be perfectly conductive and infinite in length, with two different strips within a unit-cell. The formulation is based on a multimode equivalent network representation, and uses a rigorous solution for the relevant integral equation that extends the novel solution developed previously for the single-strip grating. Expressions for the elements of the multimode coupling matrices are given, together with a comparison of results for power transmitted through the grating, obtained by using the networks developed with the present method and a simple point-matching solution. Results are presented to illustrate the differences between single and double-strip gratings     

A new variational formulation, applicable to shielded and openmultilayered transmission lines with gyrotropic non-Hermitian lossymedia and lossless conductors

A new variational expression is derived for the propagation constant of inhomogeneous shielded and open planar lines with gyrotropic lossy substrates. It yields rapidly convergent results even when higher order modes are considered. Results obtained on open and shielded lines and structures agree very well with experimental results. The efficiency of the formulation is such that calculations are made on-line on a regular PC     

Analyse rigoureuse d’antenne diélectrique microruban uniforme à ondes de fuite

In this paper, a contribution to uniform micro-strip leaky-wave antenna is presented. All its radiating characteristics are obtained, once complex propagation constant is calculated by transverse resonance combined to Galerkin method, when applying wave-guide model with magnetic walls. Then an integral formulation by application admittance operator is set where systematically an equivalent network introduces the concept of test functions. For practical reasons, only space harmonic n = - 1 is considered and its variation versus antenna dimensions is illustrated. Several examples are treated and some of the results are compared to those obtained by a spectral analysis [7,8].     

A scattering-type transverse resonance technique for thecalculation of (M) MIC transmission line characteristics

A scattering-type formulation of the transverse resonance technique is introduced and applied to a variety of currently practical (M) MIC configurations. By utilizing a reflection coefficient matrix representation of boundary conditions, the characteristics of open, conductor-backed and shielded microstrip, slotline, or coplanar waveguide can be calculated. Excellent agreement with measurements and theoretical data on fundamental and high-order mode characteristics is obtained. In contrast to other methods, which require mainframe support, the software based on this formulation is operational on 386-compatible personal computers     

Spectral analysis considerations relevant to radiation and leakymodes of open-boundary microstrip transmission line

The continuous radiation spectrum of an open microstrip transmission line and its nonspectral leaky modes are conceptualized through a transform-domain integral-operator formulation and relevant spectral analysis. The radiation spectrum is identified with branch cuts in the axial wavenumber plane, which constrain the migration of branch-point singularities in the transverse wavenumber plane. Leaky-wave modes occur only when the branch cuts in the axial wavenumber plane are violated. The relationship among spectral radiation modes, nonspectral leaky-wave modes, and branch cuts in the axial wavenumber plane is discussed. The influence of branch cuts in the axial wavenumber plane upon the location of branch points in the transverse wavenumber plane is detailed, and a rationale is offered for the choice branch cuts in the latter plane. The formulation is applicable to a wide class of open conducting or dielectric waveguides     

Studies of Semiconductor Lasers of the Interferometric and Ring Types

In this paper we present an analysis of semiconductor lasers of the interferometric and ring types, using the scattering-matrix formulation. The purpose of our analysis is to find new applications for semiconductor lasers beyond serving merely as a source for coherent radiation. Potential applications include wavelength stability, possibility for wavelength tuning and switching, operation as a traveling wave laser, and possible reduction in feedback effect. An initial set of experiments has been carried out and the results have borne out some theoretical predictions. These lasers should offer promises for use in integrated optics and fiber optical communication. Furthermore, the scattering-matrix formulation should be useful in treating other complex laser structures and lasers in an optical network environment.     

A new solution for TE plane-wave scattering from a symmetricdouble-strip grating composed of equal strips

The paper presents a new rigorous solution for the problem of TE plane-wave scattering from a periodic planar symmetric double-strip grating, i.e., the grating which has two equal strips per unit cell. The grating is placed at a dielectric interface and is assumed to be perfectly conductive and infinite in length and width. The formulation is based on a multimode equivalent network representation and the relevant integral equation defined on two separate intervals is rigorously solved by reducing to two simpler equations with known solutions. From this a new simple analytic expression is obtained for the coupling matrix elements which involves no integration. Some computations based on this new expression are carried out and the results are compared to those obtained by the Riemann-Hilbert method and also to some of the previously obtained single-strip results in the limiting case     

Analysis of Microstrip Resonators

An accurate and efficient method was developed for computing the resonant frequencies of microstrip resonators. The formulation of the problem was carried out rigorously using the full-wave analysis rather than the quasi-static approximation. The characteristic equation was derived using Galerkin's method applied in the Fourier transform domain. The accuracy of the method has been proven by comparing the numerical results with the experimental data. Numerical data have been provided for the microstrip resonators with different structural parameters. Finally, the results for microstrip resonators have been used for predicting the end effect at the open end of microstrip structures.     

用于计算微波集成电路传输特性的横切面谐振散射模型理论

本文将介绍,适用于目前较为实用的微波集成电路(MIC)各种传输结构的,横切面谐振技术的散射模型方程。通过使用反射系数矩阵来表示边界条件,该方程可算出无金属衬底、有金属衬底、屏蔽的微带线,槽线,及共面波导的传输特性。在基模和高次模的情况下,经计算所得传输特性与理论数据相比,是非常相符的。与其它模型的计算方法相比,该方程的计算软件不必在计算机主机上运行,只需在386型微机上进行运算即可。     

Full vectorial finite element formalism for lossy anisotropicwaveguides

An efficient computer-aided solution procedure based on the finite-element method is developed for solving general waveguiding structures containing lossy, anisotropic materials. In this procedure a formulation in terms of the transverse magnetic field component is adopted and the eigenvalue of the final matrix equation corresponds to the propagation constant itself. Thus one avoids the unnecessary iterations which arise when using complex frequencies. To demonstrate the strength of the presented method, numerical results are shown for a rectangular waveguide filled with lossy anisotropic dielectric with off-diagonal elements in a permittivity tensor and compared with those obtained by the telegrapher equation method. The results are in excellent agreement both for phase and for attenuation     

Analysis of single and coupled microstrip lines on anisotropicsubstrates using differential matrix operators and the spectral-domainmethod

A differential matrix operator technique is presented to simplify the formulation of boundary-value problems for open millimeter-wave integrated circuits that use anisotropic substrates. The spectral-domain method is applied to analyze the propagation characteristics of single and coupled microstrip lines printed on anisotropic substrates whose properties are described by both [∈] and [μ] tensors. In addition to considering the permittivity and permeability as a uniaxial or biaxial tensor, the effects of coordinate misalignment between the principal axes of [∈] and those of the structure in the transverse plane are also included. It is shown that the misalignment in [∈] and the presence of the [μ] tensor have a significant effect on the dispersive properties of these two structures     

Calculating the Characteristic Impedance of Finlines by Transverse Resonance Method

The characteristic impedance of finlines with up to three slots is calculated by a rigorous hybrid-mode analysis which includes the finite metallization thickness and finite depth of the mounting grooves. The transverse resonance principle utilized reduces considerably the order of the involved matrix eigenvalue problem. The propagation constants for the fundamental HE/sub 1/ mode (and EH/sub 0/ mode at related structures), as well as for the higher order modes (up to HE/sub 7/), and the characteristic impedances for the fundamental modes are computed as a function of frequency for the bilateral and unilateral finline, as well as for the unilateral finline with two coupled slots, and an additional slot on the opposite side of the substrate surface. The finite metallization thickness and mounting groove depth considered show significant influence on the behavior of the characteristic impedance.     

A novel theory for dielectric-inset waveguide leaky-wave antennas

A type of leaky-wave antenna that is particularly suitable for applications in the millimeter-wave range is analyzed. The objective of this work is to provide a practical and accurate theory for the design of this class of antennas. The analysis procedure is based on the development of a novel, multimode transverse equivalent network representation. All mutual coupling effects are rigorously taken into account. A single dispersion relation is derived via a transverse resonance procedure, and the complex dispersion behavior of the antenna is obtained through its numerical solution. Useful approximate initial design formulas are given, and a detailed parametric analysis is carried out, showing the effects of changes of all the structural parameters. The results obtained indicate that the structure, in addition to being mechanically simple to realize, exhibits a very flexible electrical behavior. The theory developed, therefore, is a powerful tool for the design and optimization of this class of antennas