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.     

Forming electrodes for a relativistic electron ribbon beam

The field structure in the Laplacian region exterior to a strip bipolar relativistic electron beam is studied. On the basis of the exact solution of the problem, the distortion of the situation symmetry caused by relativistic effects and the validity of ultrarelativistic expressions are assessed.     

Geometrized theory of narrow electrostatic electron beams with a straight axis and an arbitrary cross section

On the basis of the geometrized theory, an algorithm for calculating narrow spatial electrostatic beams is formulated. It consists in determining the metric and the transverse derivatives of the parameters of a flow on a rectilinear axis, which most often occurs in technical applications.     

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     

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。     

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.     

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     

Second-harmonic generation in birefringent crystals by a Gaussian beam with an elliptical cross section

The theory of second-harmonic generation (SHG) in birefringent crystals by a Gaussian beam with an elliptical cross section is developed in the assumption of no depletion of the fundamental beam. This study reveals that the doubling efficiency at optimum elliptical focusing is higher than at optimum circular focusing.     

Space charge waves on an unfocused cylindrical electron beam

The effect of including the magnetic force in the dynamics of a cylindrical electron beam without the focusing magnetostatic field is discussed.     

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     

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。     

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     

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.     

A Paraxial approximation of the problem of formation of nonparaxial conical and toroidal electron beams of an arbitrary cross section

A paraxial solution is constructed for the problem of calculation of forming electrodes for non-paraxial cuts from converging and diverging flows in a spherical diode and a Meltzer flow with circular paths. The solution is expressed in elementary functions for the case of a cone. For example, computations for a square on a sphere (the first approximation of the approximation of a contour) and a toroid with a circular cross section are presented.     

Analytic method of arbitrary cross section open groove guide

Groove guide is one of the waveguides that have been used at millimeter and submillimeter waveband. This paper analyzes arbitrary groove guides by means of the eigen-weighted boundary integral equation method that uses the eigenfunctions of a fictitious regular boundary as weighting functions. In comparison with the theoretical and experimental results published, the numerical results for rectangular, circular and V-groove guides using this method are exact enough with fast convergence and less calculation.     

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.     

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     

The problem of the formation of a cylindrical electron beam

Various forms of a solution to the problem of the formation of a cylindrical electron beam and the possibility of extending the approaches employed earlier to the more complicated cases of the formation of electron and electron-ion streams are discussed.