Showing papers in "Electromagnetics in 1993"
TL;DR: In this article, a scheme of reconstructing frequency dependences of S-matrices by the known sets of complex eigen frequencies has been constructed, due to which one can carry out an effective analysis of the resonance properties of diffraction characteristics of various modes.
Abstract: A number of relationships are given in this paper which allow to connect the values of S-matrices elements of open nodes with a discrete spatial spectrum (waveguides and gratings) on various sheets of analytic continuation of a frequency parameter, to find zeroes of these elements, etc. According to it, a scheme of reconstructing frequency dependences of S-matrices by the known sets of complex eigen frequencies has been constructed. A number of simple expressions are presented due to which one can carry out an effective analysis of the resonance properties of diffraction characteristics of various modes.
28 citations
17 citations
17 citations
TL;DR: The emphasis in this paper is to consider bodies that are large compared to the wavelength to suppress the spurious internal resonances and to minimize the amounts of computer time and memory storage.
Abstract: Integral equation formulations are used for the modelling of axisymmetric perfectly or imperfectly conducting scattercrs (the Leontovich boundary condition is then assumed to be verified). Our emphasis in this paper is to consider bodies that are large compared to the wavelength. We outline the methods implemented, some of which are original. Particular care has been taken in order to suppress the spurious internal resonances and to minimize the amounts of computer time and memory storage. The numerical examples presented, performed on a wide variety of objects, show that a. high degree of numerical accuracy is achieved in the high frequency domain even in the angular range where the Radar Cross Section is low.
14 citations
TL;DR: In this article, a transient analysis of coupled dispersive lossy multiconductor transmission lines with arbitrary linear or nonlinear terminations, based on an Extended Scattering Matrix (ESM) formulation, is presented.
Abstract: A new method is presented for transient analysis of coupled dispersive lossy multiconductor transmission lines with arbitrary linear or non–linear terminations, based on an Extended Scattering Matrix (ESM) formulation. This method guarantees short time domain Green’s functions, a fast simulation algorithm and relatively small memory requirements. At each point in time, both sides of the transmission line structure are represented by an extended Thevenin (or Norton) model, consisting of a real constant impedance (or conductance) matrix and a time dependent voltage (or current) source vector. This equivalent model can be implemented in existing simulation programs. Some examples with linear and non–linear loads are presented to illustrate our approach.
12 citations
TL;DR: In this article, the Morse points and the arising intertype oscillations were studied for a cavity open resonator and the one study inclusions with dielectric, and fundamental changes of ideas concerning the processes in electrodynamics including the classification of fundamental frequencies were made.
Abstract: A necessity of introducing into the spectral analysis the concept of non–degenerated (degenerated) Morse critical points due to which one can completely explain an effect of intertype oscillations is substantiated. To this end the Morse points and the arising intertype oscillations are studied for a cavity open resonator and the one study inclusions with dielectric. The of the Morse points of the open resonator dispersion equation leads to fundamental changes of ideas concerning the processes in electrodynamics including the classification of fundamental frequencies.
11 citations
TL;DR: In this article, the spectral and diffraction characteristics of cylindrical resonators loaded on various cylinrical or coaxial waveguides are investigated and the partial inversion method is used to solve this class of problems and to develop corresponding numerical algorithms.
Abstract: Spectral and diffraction characteristics of cylindrical resonators loaded on various cylindrical or coaxial waveguides are investigated The partial inversion method is used to solve this class of problems and to develop the corresponding numerical algorithms It is demonstrated that the observed effects of total resonant reflection and transmission are caused by the excitation of induced oscillations close to the eigenmodes of the problem The spectral domain solution enables us to predict the effects of complete mode transformation by open waveguide resonators (OWR) Detailed investigation of coupled eigenmodes in OWRs has determined that the phenomenon is due to the Morse critical points (MCP) of the characteristic determinant of the boundary value problem
10 citations
TL;DR: In this article, a new mathematically correct method which equivalently reduces initial boundary value problems to the infinite algebraic system of the second kind is presented, which enables us to solve the considered problem with an arbitrary settled accuracy.
Abstract: There exist many methods of analyzing electromagnetic fields scattered by thin unclosed screens of arbitrary configuration. But all these methods as a rule result in ill-conditioned matrices; that is the condition number of these matrices rapidly increases together with the matrix size. So far these methods cannot guarantee the solution with the settled accuracy. These paper presents a new mathematically correct method which equivalently reduces initial boundary value problems to the infinite algebraic system of the second kind. The truncated matrices condition numbers of this system are uniformly bounded. It enables us to solve the considered problem with an arbitrary settled accuracy. Theoretical estimates and numerical experiments demonstrated higher quality of the algorithms obtained. We also present some numerical results illustrating the possible applications of the method.
10 citations
TL;DR: In this article, under which conditions such a splitting is unique, both in infinite space and in a finite volume, a vector field can be split into an irrotational part (curl = 0) and a solenoidal one (div = 0).
Abstract: A vector field can be split into an irrotational part (curl = 0) and a solenoidal one (div = 0). This tutorial paper discusses under which conditions such a splitting is unique, both in infinite space and in a finite volume. In the latter case, multiply-bounded and multiply-connected regions must be considered separately, and electric and magnetic splittings are possible, depending on the boundary conditions imposed on the potentials.
9 citations
TL;DR: In this paper, a mathematical model for the evaluation of the backscattering by a perfectly conducting 90° dihedral corner has been developed by adding the Physical Theory of Diffraction (PTD) correction term to the Improved Physical Optics (IPO) model, which takes into account also the lighting of each face by the rays diffracted from the edge of the other one.
Abstract: A very accurate mathematical model for the evaluation of the backscattering by a perfectly conducting 90° dihedral corner has been developed. It has been obtained by adding the Physical Theory of Diffraction (PTD) correction term to the Improved Physical Optics (IPO) model, which takes into account also the lighting of each face by the rays diffracted from the edge of the other one. The agreement of such a model with the experimental results has been found very good.
9 citations
TL;DR: In this paper, an accurate numerical-analytical method of solution of the problem of wave diffraction by a perfectly conductive cylindrical body with a cross-section formed by crossing of the key elements (such as flat strips and cylinders) is proposed.
Abstract: An accurate numerical-analytical method of solution of the problem of wave diffraction by a perfectly conductive cylindrical body with a cross-section formed by crossing of the “key” elements (such as flat strips and cylindrical screens) is proposed. It is based on the ideas of the moment method and the partial inversion technique of the initial problem operator. For this problem, Gegenbauer polynomials form a complete orthogonal system of the basic functions. As a result, the initial problem is reduced to the solving of infinite systems of linear algebraic equations. Examples of the flat strip, two crossing cylinders (the cylindrical body with an ogival cross-section) and four quadrangular bodies are studied. Surface current density distributions, total scattering cross sections and radiation patterns are investigated by means of computer calculations.
TL;DR: The method of electrodynamic averaging is described in this article, by which one can obtain the effective dielectric permittivity of volume anisotropic structure determined by the shape of particles, their geometrical sizes, electromagnetic parameters and spatial dense media, to consider multiple interactions between scattering elements and dispersion properties of the media.
Abstract: The method of electrodynamic averaging is described, by which one can obtain the effective dielectric permittivity of volume anisotropic structure determined by the shape of particles, their geometrical sizes, electromagnetic parameters and spatial dense media, to consider multiple interactions between scattering elements and dispersion properties of the media. Tensors of the dielectric permittivity of anisotropic structures are given as the dielectric permittivity of media which sizes and electromagnetic parameters are fluctuating near the average values. The known formulae of dielectric mixing theory are derived from the obtained results in a numbers of cases.
TL;DR: In this paper, the theory of local excitation of one-dimensionalally periodic structures is presented, based on a study of dispersion properties of gratings as open periodic waveguides.
Abstract: Fundamental results of the theory of local excitation of one-dimensionally periodic structures are presented. The theory is based on a study of dispersion properties of gratings as open periodic waveguides. Figures illustrate new effects and phenomena detected on carrying out numerical experiments.
TL;DR: In this article, the results of investigations of a new highstable source of electromagnetic oscillations of the EHF range, namely, a diffraction radiation generator (DRG), are presented.
Abstract: The paper deals with the results of investigations of a new highstable source of electromagnetic oscillations of the EHF range, namely, a diffraction radiation generator (DRG). Its operating principle is based on using the effect of diffraction radiation (Smith-Parcel effect). Technical specification of the DRG and examples of their application in radisystems are given.
TL;DR: In this article, an analysis of two-dimensional scattering from an unclosed circular cylinder in the vicinity of the plane penetrable interface between two semi-infinite homogeneous half spaces of the same or of different electromagnetic properties is presented.
Abstract: An analysis of two-dimensional scattering from an unclosed circular cylinder in the vicinity of the plane penetrable interface between two semi-infinite homogeneous half spaces of the same or of different electromagnetic properties is presented. The perfectly conducting axially slotted cylinder is of infinite extent and the excitation is transverse electric to the cylinder axis. The final infinite system of linear algebraic equations for expansion coefficients of the current density function is obtained from the dual series equations by the method of Riemann-Hilbert Problem. The system may be solved by truncation of an infinite matrix with further usage of ordinary inversion methods. The cylinder is excited by a plane wave or by a line magnetic-current source. Some data displaying the frequency dependencies of the scattering cross-section and radiation resistance, as well as the far-field patterns, are presented and discussed.
TL;DR: In this paper, a vector wave function approach with dyadic analysis is used to expand the fields, producing all components of the dyadic Green's functions in one solution, making application to the analysis of shielded transmission lines very straightforward including the calculation of the fields in all layers.
Abstract: A full-wave, integral equation method is presented which generalizes the treatment of multi-layer substrates and superstrates for shielded circuits so that any combination and number of layers can be handled without reformulation. A vector wave function approach with dyadic analysis is used to expand the fields, producing all components of the dyadic Green's functions in one solution. The approach makes application to the analysis of shielded transmission lines very straightforward including the calculation of the fields in all layers. Application to the determination of fundamental properties of strip transmission lines are emphasized in the examples provided.
TL;DR: In this paper, an iterative loop-EMFIMF method for quantifying the induced EM field in a finite, heterogeneous, non-magnetic body irradiated by an incident EM field has been developed.
Abstract: A new numerical method, iterative loop-EMF method, for quantifying the induced EM field in a finite, heterogeneous, non-magnetic body irradiated by an incident EM field has been developed. In this method, the body is modeled by an impedance network and Faraday's law is used to relate the induced loop electric field (or current) to the induced magnetic field. In the mean time, a coupled tensor field integral equation is used to iterate the induced electric and magnetic fields. This method can improve numerical accuracy of the existing tensor electric field integral equation method. The theoretical analysis and numerical examples are both presented. Good agreement is obtained by the comparison with the previous published results.
TL;DR: The properties of the image slot line (ISL), the fundamental mode of which is a quasistatic slot quasiwave have been considered, i.e., spectrum, operating frequency band, overall dimensions, attenuation and wave resistance as discussed by the authors.
Abstract: The properties of the image slot line (ISL), the fundamental mode of which is a quasistatic slot quasiwave have been considered, i.e. spectrum, operating frequency band, overall dimensions, attenuation and wave resistance as well as modifications of the ISL, differing in the cross-section shape and being used as a base for various functional units.
TL;DR: In this article, a mathematically rigorous solution for the diffraction problem of electromagnetic waves on an axially symmetric system of two infinitely thin perfectly conducting spherical caps is obtained for both open resonators with spherical mirrors and two mirror spherical antennas.
Abstract: A mathematically rigorous solution is obtained for the diffraction problem of electromagnetic waves on an axially symmetric system of two infinitely thin perfectly conducting spherical caps. This screen configuration is a model of both open resonators with spherical mirrors and two mirror spherical antennas. The initial boundary problem is equivalently reduced to the infinite system of linear algebraic equations of the form (I + H)x = b with the compact operator H in the Hilbert space l 2; the reduction is done using the variables separation technique in the local coordinates, theorems on addition of the Debye potentials, and the regularization technique for dual series equations involving the Jacobi polynomials. The spectrum of complex eigen frequencies of an open resonator with spherical mirrors is calculated, and classification is established for its own modes. Application boundaries are obtained for quasi-optical models of open resonators. A new theoretical model is suggested for the phenomen...
TL;DR: In this paper, the problem of finding propagation constants and field components of the shielded slot lines with the conductors of finite thickness and arbitrarily located slots is formulated as a boundary value problem for Maxwell equations.
Abstract: The problem of finding propagation constants and field components of the shielded slot lines with the conductors of finite thickness and arbitrarily located slots is formulated as a boundary value problem for Maxwell equations. The spectral domain approach is used to construct a mathematical model. The developed numerical algorithm provides accurate and high-speed computation of the propagation constants and field components of the dominating mode and of any number of the higher-order propagating ones. Numerical results are presented.
TL;DR: In this paper, the experimental results of wave modes "coupling" excited by electron flow in open resonator of diffraction generator are presented with due regard for the concept of Morse critical point.
Abstract: Results of experimental research of wave modes “coupling” excited by electron flow in open resonator of diffraction generator are presented. With due regard for the concept of Morse critical point the conditions resulting in working wave modes forking and coupling following are visually demonstrated.
TL;DR: In this paper, the problem of scalar wave scattering from a thin spherical segment is posed in Neumann's formulation and reduced by means of the rigorous method solution to infinite system of linear algebraic equations (SLAE).
Abstract: The problem of scalar wave scattering from a thin spherical segment is posed in Neumann's formulation and reduced by means of the rigorous method solution to infinite system of linear algebraic equations (SLAE). To solve this system using a contemporary computer by such a direct method as that of Gauss the size of the extracted closed matrix of SLAE is to be no more than a few hundreds. It is the very reason that restricts variety of solvable diffration problems. On using the special matrix structure and technique of the fast Fourier transform the new iterative algorithm has been put into practice. The new method permits to increase the order of computable SLAE to a few thousands, hence to expand the abilities of numerical calculations in the quasi-optical frequency range. The realized numerical investigations have demonstrated high computational efficiencv of the new algorithm. The scattered fields in near- and far-field zones have been compared qualitatively with those obtained by means of phys...
TL;DR: In this paper, the transmission line problem for shielded fin-line structures is studied using integral representation of the field by means of Green's potentials, which is reduced to the eigenvalue problem for the singular integral operator-valued function.
Abstract: The transmission line problem for shielded fin-line structures is studied using integral representation of the field by means of Green's potentials. It is reduced to the eigenvalue problem for the singular integral operator-valued function. Galerkin method is applied for calculating frequency-dependent propagation constants of the normal waves and field components on the slots and strips. Numerical results for the dominant and higher-order modes in various structures are presented.