Boundary-marching method for discontinuity analysis in waveguidesof arbitrary cross section

A recursive algorithm previously used in diffusion problems of geophysics and in electrostatics is extended to wave phenomena. It is used to construct a matrix representation for an infinitely long waveguide of arbitrary cross-sectional shape. This representation is used in finite-element analysis of waveguide discontinuities. In numerical tests, scattering matrices for the long guides converge to nearly full word-length in six to seven recursion steps, and discontinuity characteristics are within 1-2% of known results where they exist     

Electrooptic modulation in an arbitrary cross section waveguide

The electromagnetic field of an optical wave of frequency ω, traveling through a long, electrooptic waveguide of arbitrary cross section and composition in the presence of an arbitrary external field of strength E^ext and radio frequency Ω, is derived by a perturbative argument, assuming Ω/ω≪1 and | r_ijkE^ext|≪1, where r _ijk are the linear electrooptic coefficients. An idealized model is solved exactly in the context of rigorous perturbation theory, and the solution is shown to be valid whenever (r_ijk E^ext)²ω/Ω≪1, without restriction on r_ijkE^extω/Ω. The arbitrary cross section formula, when evaluated in the model case, agrees exactly with the rigorous result, so it is argued that the arbitrary cross section formula should also be valid whenever (r_ijkE^ext)² ω/Ω≪1     

Analysis of dielectric waveguide structure of arbitrary cross section

A class of dielectric waveguide structures of arbitrary cross section in conjuction with one or more layer dielectrics is ana lysis with the Method of Lines(MOL). This leads to an eigenvalue problem where the nonphysical and spurious modes do not appear. Dispersion characteristic examples are calculated for structures suitable for mm waves and optical integrated circuits. Such as ridge guides, guide, and so on. The numerical examples are verified by results available from other methods.     

Scattering by a chiral cylinder of arbitrary cross section

An integral equation and method-of-moments (MM) solution to the problem of scattering by an inhomogeneous chiral cylinder of arbitrary cross section is presented. The volume equivalence theorem for chiral media is developed and used to formulate a set of coupled integral equations for the electric and magnetic volume polarization currents representing the chiral cylinder. These coupled integral equations are solved using a standard pulse basis and point-matching MM solution. Numerical results, including echo width and internal fields, are presented for the scattering by chiral slabs and circular cylinders. These results are compared to exact solutions when available     

Finite-element analysis of dispersion and loss characteristics of groove guide with arbitrary shapes

The dispersion and loss characteristics of groove guide with arbitrary shapes are analyzed with high-order finite element method. The effectiveness and the reliablity of the method are verified by the experiments and the results obtained by other methods. Groove guides with various groove shapes, such as rectangular, triangular, parabolic, elliptic and cosine functions, are investigated systematically. The calculating results show that the dispersion of groove guide with different groove shape is almost the same, however, the loss characteristics is rather different; among them, V-shape groove guide has the lowest loss which is about half of the rectangular one. All the curves and the data given in this paper can be used in designing elements and circuits of the groove guide.     

Scattering cross section of a small radome of arbitrary shape

A simple moment procedure is used to compute the scattering cross section of a small radome of arbitrary shape. Numerical results are presented for a radome with Von Karmon shape and a spherical shell. The computed and exact results for the spherical shell are in good agreement. Data for the Von Karmon shape are presented but not yet assessed. The method presented is found to be mainly limited to radomes in the resonance region since as the size of radome increases, the number of unknowns required for reasonable convergence drastically increases     

单轴双各向异性媒质柱体的电磁散射

采用广义多极子技术（Ｇｅｎｅｒａｌｉｚｅｄ Ｍｕｌｔｉｐｏｌｅ Ｔｅｃｈｎｉｑｕｅ,ＧＭＴ）分析了单轴双各向异性媒质任意截面柱体的电磁散射,计算结果与解析解和矩量法（Ｍｅｔｈｏｄ ｏｆ Ｍｏｍｅｎｔｓ,ＭｏＭ）所得结果一致,讨论了该方法在电磁散射应用中的优缺点。     

Scattering by a dielectric cylinder of arbitrary cross section shape

The theory and equations are developed for the scattering pattern of a dielectric cylinder of arbitrary cross section shape. The harmonic incident wave is assumed to have its electric vector parallel with the axis of the cylinder, and the field intensities are assumed to be independent of distance along the axis. Solutions are readily obtained for inhomogeneous cylinders when the permittivity is independent of distance along the cylinder axis. Although other investigators have approximated the field within the dielectric body by the incident field, we treat the total field as an unknown function which is determined by solving a system of linear equations. In the case of the dielectric cylindrical shell of circular cross section, this technique yields results which agree accurately with the exact classical solution. Scattering patterns are also presented in graphical form for a dielectric shell of semicircular cross section, a thin homogeneous plane dielectric sheet of finite width, and an inhomogeneous plane sheet. The effects of surface-wave excitation and mutual interaction among the various portions of the dielectric shell are included automatically in this solutiom     

Radiation from apertures in conducting cylinders of arbitrary cross section

An analysis of two-dimensional radiation from apertures in perfectly conducting cylinders of arbitrary cross section is given. Solutions are expressed in terms of generalized network parameters, obtained by applying moment methods to the superposition integral equation. Formulas are given for current distributions, self- and mutual admittances, and radiation patterns. Representative computations are included to illustrate the theory.     

任意截面波导的模式截面场的数值分析

给出了任意截面波导的传输特性的时域差分（FDTD）数值方法的一般分析方法,首次提出了用数值方法建立任意截面波导中各模式横向场分量截面场分布的方法,为证明这种方法的有效性,计算了常用空气填充的Ka波段矩形波导中主模（H10模）和一次高阶模式H20模的截止波长和Ey场分量,其与理论值的安全一致性表明所提出的方法是正确的。作为应用例子给出了一种新型的五边形波导的最低四个模式的传播常数及主模式和第一高次模的电场在波导横截面的场分布图。     

Backscatter of a large rotating conducting cylinder of arbitrary cross section

A quasi-stationary method in conjunction with geometrical theory of diffraction (GTD) techniques is used for calculating the backscattered field from a large rotating conducting cylinder with an arbitrary cross section. Using this method, the scattered field at each timetis obtained as if the cylinder were stationary. The power density spectrum is then obtained using a Fourier transform. The backscattcr power density spectrum of a large rotating cylinder consists of discrete spectral lines. For an orthogonal polygon-cylinder rotating about its geometrical center axis, the backscatter power density spectrum is symmetric about the incident frequency.     

Formation of a bipolar conical beam with an arbitrary cross section

Problems of calculating forming electrodes for fragments of a bipolar diode that have the form of a circular cone or a cone with an arbitrary cross section are considered. Local characteristics of cathode and anode equipotential surfaces are obtained, and their dependence on the configuration of the contour bounding the beam’s cross section is revealed. Theoretical aspects of the technology of manufacturing 3D optoelectronic systems (templates for electrodes) are investigated. The effect of a beam on plane targets of given shapes is studied. Forming electrodes for a relativistic injector with a conical electron beam having an arbitrary cross section are constructed.     

Study of coupling between circular groove guide and rectangular groove guide

On the basis of the studies of single circular groove guide and single rectangular groove guide, the coupling of the two waveguides has been researched and the characteristic equation of circular—rectangular groove guide has been given in this paper.     

Self-consistent GTD formulation for conducting cylinders with arbitrary convex cross section

A user-oriented computer program has been developed for high frequency radiation and scattering from infinitely-long perfectly. conducting convex cylinders. The analysis is based on the self-consistent geometrical theory of diffraction (GTD). The cylinder is modeled as anN-sided polygon. Two cylindrical waves with unknown amplitudes are assumed to travel in opposite directions on each face of the polygon. The boundary conditions for the corners are applied to set up a matrix equation for2Nunknowns (the amplitudes associated with the traveling cylindrical waves). Crout's method is used to solve the matrix equation. Once the amplitudes for the traveling waves are determined, the radiation or scattered field is readily obtained via the usual GTD techniques. Numerical results are presented for radiation and scattering from rectangular, semi-circular, circular, and elliptic cylinders for both principal polarizations. The results show excellent agreement with GTD, moment, and eigenfunction solutions.     

Rigorous combined mode-matching integral equation analysis of hornantennas with arbitrary cross section

A combined rigorous method is presented for the analysis of horn antennas with arbitrary cross section and general outer surface. The horn taper is described by the mode-matching (MM) method where the cross-section eigenvalue problem is solved by a two-dimensional (2-D) finite element (FE) technique. For the exterior horn surface including the radiating aperture, the application of the Kirchhoff-Huygens principle yields two expressions for the admittance matrix which are based on the electric (EFIE) and the magnetic (MFIE) field integral equation, respectively. The equations are solved numerically by the method of moments (MoM). For the preferred EFIE formulation, the eigenvectors of the last waveguide taper section and RWG functions for triangular patches are utilized as basis-functions for the magnetic or electric surface current densities, respectively. The presented method is verified by available reference values or measurements for a waveguide radiator with a peripheral choke, a conical and a rectangular horn. Its flexibility is demonstrated at the example of a conical ridged waveguide horn     

Forming electrodes for a cylindrical electron beam with an arbitrary cross section

A new form of the exact solution to the exterior problem for a beam representing a fragment of an electron flow with an arbitrary cross section in a planar diode is obtained in the case of emission in the ?? mode. Particular forms of the general expression for circular and elliptical cross sections are presented. The case of a temperature-limited emission is considered.     

RCS of two-dimensional structures consisting of both dielectricsand conductors of arbitrary cross section

The problem of determining the electromagnetic field scattered by two-dimensional structures consisting of both dielectric and conducting cylinders of arbitrary cross section is considered. The conductors may be in the form of strips and the dielectrics may be in the form of shells. The conductors may be partially or fully covered by dielectric layers, while the dielectrics may be partially covered by conductors. Only homogeneous dielectrics are studied. Both the transverse electric (TE) and the transverse magnetic (TM) cases are considered. The problem is formulated in terms of a set of coupled integral equations involving equivalent electric and magnetic surface currents radiating in unbounded media. The method of moments is used to solve the integral equations. Simple expansion and testing procedures are used. Numerical results for scattering cross sections are given for various structures     

Calculation of radiation patterns of microstrip antennas oncylindrical bodies of arbitrary cross section

A simplified approach based on reciprocity is presented to calculate the radiation patterns of microstrip patch antennas or arrays on a cylindrical body having an arbitrary cross section. In this approach, the microstrip patch antennas are characterized using the finite-element method, and their radiation patterns are then calculated using a two-dimensional method of moments in conjunction with the reciprocity theorem. The validity of the calculation is demonstrated by comparison with measured data for a microstrip patch antenna on a circular cylinder attached to a plate. Other numerical examples are also presented to show the capability of the method as well as various effects of the host cylinder on radiation patterns     

Field singularities at the tip of a metallic cone of arbitrary cross section

The "spherical-harmonics" problem is investigated for a cone of arbitrary cross section. The analysis shows that two basic singularities must be considered: 1) the electric singularity, in whichbar{e}becomes infinite likeR^{nu-1}near the tip of the cone, 2) the magnetic singularity, in whichbar{h}becomes infinite likeR^{tau-1}. Numerical results, in particular concerningnuandtau, are given for: 1) the elliptic cone and its limiting case the sector, 2) the pyramidal corner.