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Mathematical Methods in Electromagnetic Theory, 1996., 6th International Conference on

Date 10-13 Sept. 1996

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Displaying Results 1 - 25 of 130
  • MMET '96. VIth International Conference on Mathematical Methods in Electromagnetic Theory. Proceedings

    Publication Year: 1996
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  • Selection of regularization parameters of inverse problem by computer simulation model

    Publication Year: 1996 , Page(s): 478 - 480
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  • Author's index

    Publication Year: 1996 , Page(s): 533 - 535
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  • Wave diffraction by semi-infinite system of partially transmitted layers

    Publication Year: 1996 , Page(s): 96 - 99
    Cited by:  Papers (2)
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    Various techniques have been developed for analyzing electromagnetic wave diffraction by a system of finite number of obstacles and periodic structures. Some numerical difficulties can be overcome by using the solution of the problem of electromagnetic wave diffraction by semi-infinite discrete structure. In this paper we develop some new methods for numerical calculation of the reflection operator of a semi-infinite system of partly transmitted layers View full abstract»

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  • Analysis of finite antenna arrays composed of finite length shielded disk-on-rod structures

    Publication Year: 1996 , Page(s): 302 - 305
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    The problem of accurate prediction of radiation characteristics of microwave planar finite antenna arrays composed of finite length cylindrical shielded disk-on-rod structures fed by the H11 mode is considered. The solution is based on an integral equation and Green's function approach and takes into account the mutual coupling between arbitrary propagating and evanescent eigenmodes in the array elements. It is shown that predicted and measured radiation characteristics of the designed 9-element array are in good agreement. Thus, the developed algorithm and computing code have a considerable potential in design of finite antenna arrays comprising circularly symmetric radiating elements viz circular waveguides, conical and profiled horns, coaxial waveguides and horns, disk-on-rod structures in circular waveguides, disk-on-cones, etc View full abstract»

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  • Electromagnetic waves transmission through grounded waveguide with scatterers

    Publication Year: 1996 , Page(s): 179 - 182
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    Investigation of the properties of fields, diffracted on a system of scatterers in a stratified medium, is an important problem of modern radiophysics. Description of such phenomena in the resonance frequency range, where the wavelength is close to the scatterers' dimensions, is possible only with a rigorous solution of the corresponding diffraction problem. Significant difficulties arise when the scattered field is calculated in the case of arbitrary scatterer geometry. One way to solve the problem of scalar electromagnetic wave diffraction in the H-polarized case on scatterers in a stratified medium is proposed View full abstract»

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  • The resonance on small non-homogeneity in the waveguide

    Publication Year: 1996 , Page(s): 369 - 372
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    The solution of the initial-boundary value problem for the wave equation depending on the small parameter ε, with the right-hand side which is periodic in time with frequency ω, is researched View full abstract»

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  • Subsurface layer statistical resonance

    Publication Year: 1996 , Page(s): 267 - 270
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    When considering the scattering of waves by a layered medium with a rough surface, the correlator Q=⟨E(ω)E(ω)⟩ is usually studied (here E and ω are the electric field of the reflected wave and the circular frequency, correspondingly). Generally, it can be expanded in a power series of the reflection coefficients V i of inner boundaries. For the case of strong scattering the terms Qi1 proportional to the first powers of Vi become as a rule exponentially small by the scattering parameter Δ=(σ/λ)2, with σ and λ being the mean square roughness height and the wave length accordingly. Only if more general correlators P are considered, then the values Pi1 prove to be not exponentially small when some resonance conditions are satisfied. We refer to this phenomena as to the subsurface layer statistical resonance. For the first time, we found that the phenomena exist in the two cases: of small jump of the dielectric constant at the medium boundary and of large-scale roughness for normal incidence of wave. In this report we generalise the last case for oblique incidence of wave. It is shown, that the resonance takes place in a specular direction for the two frequency correlator P=⟨E(ω1)E(ω2)⟩ with the resonance condition ω1,22,1(√(ε-sin2 θ)/cosθ-1). Here ε and θ are the layer dielectric constant and the incident angle, accordingly. The resonance width and amplitude are studied and discussed View full abstract»

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  • Modeling of semiconductor laser with large signal modulation

    Publication Year: 1996 , Page(s): 416 - 419
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    The problem of simulating direct modulation with a large signal is treated. The singularity of the given type of modulation is that there is no general analytical solution for the modulation with current pulses similar to the analytical solution for the modulation with a sinusoidal signal (small-signal model). Dynamic characteristics of semiconductor bulk lasers and quantum well structure lasers are well described by the rate equation derived from the diagonal elements of the density matrix View full abstract»

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  • EM wave scattering from a slightly rough surface of an anisotropic medium

    Publication Year: 1996
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    Summary form only given. The theoretical analysis of the interaction of EM waves with anisotropic media is interesting for applications such as remote sensing, nondestructive testing and microelectronics. We consider the problem of two media, one gyrotropic and one isotropic, separated by a boundary covered by small-height and gently sloping roughness. The axis of symmetry of the gyrotropic medium is perpendicular to the unperturbed boundary. The model we use of the gyrotropic medium can describe a magneto-active plasma, a ferrite in an external static magnetic field and certain artificial dielectrics. The model of a weakly rough surface can be used to describe the lower boundary of the ionosphere and non-ideally processed surfaces of manufactured objects. Simpler scattering problems involving isotropic media only have been extensively treated in the past. This report extends the previous research to account for anisotropy of an underlying medium. We present an analytic solution for the fluctuating field using a small perturbation approach, and analyze the effect of anisotropy on the scattering pattern of random roughness View full abstract»

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  • Characteristics of planar directional couplers based on rib lightguide structure

    Publication Year: 1996 , Page(s): 100 - 103
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    The characteristics and electric field distributions of the supermodes of SOI rib waveguide based couplers are presented. The results obtained confirm that even small asymmetry of the coupler has a strong influence on the coupling length and field distribution of the supermodes View full abstract»

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  • Advance of mathematical methods of electromagnetic theory in the Karpenko Physico-Mechanical Institute

    Publication Year: 1996 , Page(s): 46 - 53
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    One of the main trends of scientific activity at the Karpenko Physico-Mechanical Institute is the investigation of the fine structure of physical fields and signals and the development of the theory and methods for their analysis. Concerning the theory of electromagnetic fields, such investigations cover the diffraction problems for harmonics in time radiation as well as the probabilistic analysis of non-stationary stochastic signals. The aim of the proposed work is to designate some results in these fields of electromagnetic theory which were obtained recently at the Institute View full abstract»

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  • Nonlinear best Chebyshev approximations and splines

    Publication Year: 1996 , Page(s): 128 - 131
    Cited by:  Papers (1)
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    The necessity of using parametric nonlinear expressions and splines arises because real physical processes are described by many different analytical dependencies. The classic technique of finding the best Chebyshev approximation is also based on nonlinear approximations. But such approximations are not always possible. The author formulates a theorem that allows one to establish the condition of existence of the best Chebyshev approximation of a chosen kind View full abstract»

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  • Measuring signal parameter estimation under object and material investigation by means of pulse electromagnetic fields

    Publication Year: 1996 , Page(s): 375 - 378
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    Pulse electromagnetic sounding is one effective method for environment, object and material physicomechanical characteristics study. The investigated environment information is contained in response signals that represent a sequence of fading voltage pulses. Under investigation, the receiving converter is also affected by a number of random and regular noises of pulse and continuous character that cause a stochastic structure of the informative signal and do not allow one to determine its informative characteristics without special processing. The processing mode of the stochastic signals depends sufficiently on their mathematical model. For the problem of registered signal parameter estimation, its mathematical model may be presented in the form of a sequence combination of its homogeneous informative elements (momentary signal meanings, durations, etc.) that are random processes View full abstract»

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  • The Kontorovich-Lebedev transform in diffraction problems for conical surfaces

    Publication Year: 1996 , Page(s): 320 - 322
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    One powerful analytical method for solution of diffraction problems in regions with conical boundaries is the method of the Kontorovich-Lebedev integral transform. The inversion formula is preferable for solution of diffraction problems or for calculation of the far field. In the case of boundary conditions such as the Dirichlet or the Neumann condition for the Helmholz equation, algebraic equations for transforms are established and solutions are found easy by means of the inversion formula. Difficulties begin in problems with boundary conditions of the third kind which depend on radial coordinates. The situation takes place for conic surfaces conducting along spirals, for instance. In this case for transforms we can obtain linear nonhomogeneous fnnctional equations with entire differences and complex coefficients including the associated Legendre functions View full abstract»

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  • Mixed potential integral equation methods for multilayered structures

    Publication Year: 1996 , Page(s): 16 - 27
    Cited by:  Papers (1)
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    Electromagnetic fields created in a homogeneous medium by a known distribution of electric current are determined by integral equations involving free space Green's functions. In actual situations, however, current distributions are not known beforehand and must be determined, in such a way that the total fields satisfy the boundary conditions on the conductors. The integral equation technique was extended to treat also heterogeneous structures, in order to analyze and design multilayer printed circuits and antennas, such as the broadband strip-slot-foam-inverted patch printed antenna. Sommerfeld integrals provide Green's functions for stratified media, which are evaluated by means of specifically developed, efficient computer algorithms. Structures including coaxial or line feeds and coupling through slots can now be easily analyzed with commercially available software packages View full abstract»

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  • Random processes statistic application for cardiosignals characteristics determination

    Publication Year: 1996 , Page(s): 264 - 266
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    Statistical analysis may considerably increase the effectiveness of ECG diagnostic methods. The statistical data analysis allows: increase of the measurement accuracy by means of sampled data number increase; decrease of the external disturbances influence on the results of measurements; increase of the information content by giving the results of investigations in a convenient and clear form; the main ECG statistic characteristics calculations to be carried out; the measuring errors to be estimated; extrapolation, interpolation, and prediction methods to be used on the ECG data; and computer use for automated calculations View full abstract»

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  • On a numerical method of a diffraction theory inverse problem solving

    Publication Year: 1996 , Page(s): 461 - 464
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    A method of a numerical solving of the Kirchoff scalar diffraction theory inverse problem is discussed. This technique is known as the method of a synthetic aperture and its application for the image constructing in side looking radars placed on the flying supporters is in wide use. But here it is applied for achieving images of dielectric medium inhomogeneities using the data of the subsurface scanning with the multifrequency electromagnetic pulses. In the work presented here a short description of the method and construction of the appropriate computational algorithm are given. Besides that results of some computational and natural experiments are discussed and this shoes a wide possibilities of the method suggested. Physical realization is presented of aperture synthesizing View full abstract»

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  • Numerical method for solving of three-dimensional scattering problems from penetrable body

    Publication Year: 1996
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    Summary form only given. We formulate the method of minimal discrepancies for solving some linear equations with a non-self-adjoint operator and prove the theorem which determines the conditions for the convergence of the iterations to the solution. In particular, this method can be applied to solve integral equations with a dissipative operator. Volume integral equations (singular equations for electromagnetic problems and Fredholm equations of the second kind for acoustic problems) which describe three-dimensional scattering problems from penetrable inhomogeneous bodies are considered. With the help of energetic inequalities the feasibility of the iterative method to obtain a solution of such integral equations is demonstrated. To approximate these equations the moment and collocation methods are applied. We prove that the approximate solution converges to the exact solution of the integral equations as the number of basis functions or collocation points tends to infinity. To reduce the computing cost, the direct and inverse discrete Fourier transforms are used. To accelerate the convergence of the iterations to the solution, the multistep minimum-discrepancy method, a generalization of the iterative procedure, is formulated and used View full abstract»

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  • The effective algorithm to calculate the Green function and its derivatives in the circular waveguide

    Publication Year: 1996 , Page(s): 132 - 135
    Cited by:  Papers (1)
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    The tensor Green function for the electric vector potential of the circular waveguide, is the superposition of the tensor free-space Green function and the regular Green function. The proposed algorithm for calculation works equally well at any spacing between the points of the source and observation and can be effectively used to calculate the linear antenna in the circular waveguide by asymptotic methods View full abstract»

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  • Numerical method for solving of electromagnetic scattering problems of three dimensional arbitrary shaped magnetic dielectric bodies

    Publication Year: 1996 , Page(s): 84 - 87
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    Variants of the discrete sources method have been developed which allow one to obtain concrete numerical results for perfectly conducting and impedance scatterers. In this paper the variant is generalized for the case when a scatterer is a magnetic dielectric one View full abstract»

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  • Universal method of the analysis of multilayered planar lines and complex guides

    Publication Year: 1996 , Page(s): 335 - 338
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    Multiconductor transmission lines arranged in multilayered dielectric medium are widely used in the design of microwave and millimeter-wave integral circuits. Plenty of work devoted to calculation of these lines was published. It is not simple even to list majority of them. Increasing the number of conductor, component density, frequency, design complexity of transmission lines needs sharply increasing volume of calculation. Therefore, the requirements of efficiency as well as high accuracy of used method become more severe View full abstract»

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  • The matrix theory of non uniform waveguide structures excitation

    Publication Year: 1996 , Page(s): 187 - 190
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    The present paper suggests a new matrix-electrodynamics method, which is based on the selection among the direct and backward waves of a more narrow class of waves, marked in correspondence with the location of excitation sources relative to the region being considered. A non-uniform waveguide structure (WS) means any fast or slow change of the form or size of its cross section, parameters of dielectric filling, metal or dielectric ledges, probes, coupling apertures, etc. As an example, the authors consider a waveguide-microstrip junction View full abstract»

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  • Energetic concept in the theory of laser sounding

    Publication Year: 1996 , Page(s): 379 - 381
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    The analysis of limits of accuracy of measurements with the help of laser sounding should take into account the known division of non-stationary processes into two classes according to attributes, essential for the correlation-spectral analysis. A mathematically strict and physically reasonable treatment of this problem gives the energy theory of stochastic signals (ETSS), making a mathematical basis for a wide class of modern algorithms of calculation for the characteristics of processes and systems. As the interaction of light with a substance has an essentially random or stochastic character, at any registration inevitable fluctuations exist, caused by the fact that light can absorb only by small discreet portions of energy or quanta. The half-classical approach gives in a maximum degree, physically clear and mathematically, the constructive description of interaction of light with a substance using a probabilistic model of a signal View full abstract»

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  • Radiation characteristics of phased antenna array situated under semi-infinite dielectric slab

    Publication Year: 1996 , Page(s): 420 - 422
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    In many cases, phase antenna arrays are placed under a dielectric slab covering. As a rule, there are metallic constructions in the edge of the slab. Surface waves appear in the dielectric slab, their amplitudes range up to a high value under special conditions. Near the edge of the slab, the surface wave energy is partly radiated and is partly reflected and thus is able to alter significantly the array pattern. An antenna array of finite size situated under the semi-infinite dielectric slab can be taken as a suitable mathematical model for the analysis of this phenomenon. In this case the slab is continued as a perfectly conducting one to the domain, where z<0. A slot antenna of infinite length is used as a radiator of the array, i.e. the considered problem is of a two-dimensional x-kind. It is solved in the approximation of predetermined magnetic currents in slot radiators View full abstract»

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