Showing papers on "Computational electromagnetics published in 1970"
TL;DR: In this paper, a new method for digitally modeling the frequency dependence of the line parameters for an overhead transmission line using Fourier transforms is presented. But the model of the frequency-dependent line is embedded in a general purpose electromagnetic transients program providing the user with a wide choice of termination and excitation conditions.
Abstract: A new method is given for digitally modeling the frequency dependence of the line parameters for an overhead transmission line. Using Fourier transforms, the method models only the line characteristics, leaving the terminations to be chosen by the user. The model of the frequency-dependent line is embedded in a general purpose electromagnetic transients program providing the user with a wide choice of termination and excitation conditions. The method promises to be accurate, and provides insight into the propagation of the aerial and ground modes of transmission. A comparison of line modeling using the method of characteristics, ?equivalents, and frequency-dependent line parameters is given. Although the frequency dependence has been implemented for only one two-phase line, the method is general in principle.
145 citations
TL;DR: In this paper, a method for determining the fields scattered by arbitrarily shaped cylindrical conducting structures with a transient incident wave is described, where the transient scattering problem is reduced to the solution of a time domain integral equation which in turn is solved directly in the time domain by means of a digital computer.
Abstract: A method for determining the fields scattered by arbitrarily shaped cylindrical conducting structures with a transient incident wave is described. The transient scattering problem is reduced to the solution of a time domain integral equation which in turn is solved directly in the time domain by means of a digital computer. The approximate electromagnetic impulse response for a number of cylindrical scatterers is calculated using this method.
92 citations
TL;DR: In this article, the authors present matrix equations for computing the scattered wave of a homogeneous gyrotropic cylinder, where an incident wave with arbitrary polarization is assumed to illuminate the cylinder, which is magnetized along its axis.
Abstract: Matrix equations are given for computing the scattered wave of a homogeneous gyrotropic cylinder. An incident wave with arbitrary polarization is assumed to normally illuminate the cylinder, which is magnetized along its axis. The reciprocity theorem is first applied to the interior of the cylinder. According to the boundary condition, one can replace the tangential components of the total wave on the inside surface by that of the sum of the incident and the scattered waves on the outside surface; the scattered wave is expanded in terms of a series of Hankel functions. Making use of the idea of Waterman's extended integral equation, one obtains the matrix equations to directly determine the expansion coefficients of the scattered wave. The matrix equations have been solved numerically on the NEAC 2200 and the HITAC 5020E for a circular ferrite (or dielectric) cylinder and an elliptic ferrite cylinder. The former solutions are shown to converge to the exact solutions, and the latter scattering patterns of interest are shown in graphical form for an E incident wave. The reciprocity theorem for scattered waves is also examined.
31 citations
29 citations
TL;DR: Using a conformal transformation, the singularities of electromagnetic fields near a sharp edge are related to the geometry of the scatterer as discussed by the authors, and the results are then used to treat the singularity of...
Abstract: Using a conformal transformation, the singularities of electromagnetic fields near a sharp edge are related to the geometry of the scatterer. The results are then used to treat the singularities of...
19 citations
TL;DR: In this article, the current distribution on the wires was obtained by solving numerically a system of integral equations, and the scattered fields and backscattering cross sections were obtained using standard techniques.
Abstract: The electromagnetic scattering from two straight wires, which intersect perpendicularly, is considered. First, the current distribution on the wires is obtained by solving numerically a system of integral equations. Then the scattered fields and backscattering cross sections are obtained using standard techniques.
19 citations
TL;DR: In this article, the radiation transport equation is studied as a means of describing the scattering of electromagnetic waves by a plasma and the approximations required to replace Maxwell's equations by a transport equation are reviewed.
Abstract: The radiation transport equation is studied as a means of describing the scattering of electromagnetic waves by a plasma. The approximations required to replace Maxwell's equations by a transport equation are reviewed. The form of the transport equation expressed in terms of Stokes' parameters is given and special expressions for backscatter are developed.
19 citations
01 Nov 1970
TL;DR: In this article, the propagation constant of the electromagnetic wave along a very thin conducting wire immersed in a magnetoplasma is obtained explicitly for a general case where the dc magnetic field is applied with an arbitrary inclination with respect to the wire.
Abstract: The propagation constant of the electromagnetic wave along a very thin conducting wire immersed in a magnetoplasma is obtained explicitly for a general case where the dc magnetic field is applied with an arbitrary inclination with respect to the wire.
14 citations
TL;DR: In this paper, two-dimensional field equations are reduced to Fredholm integral equations of the second kind and the integral equations are solved by matrix methods and the convergence of the matrix solutions is discussed.
Abstract: Two-dimensional field equations are reduced to Fredholm integral equations of the second kind. The integral equations are solved by matrix methods. The convergence of the matrix solutions is discussed. The matrix methods are applied to calculating the cutoff wavenumbers of waveguides. A method of estimating the errors is proposed. A method of correcting the matrix solutions is described and applied to a field problem in which the boundary is large compared with the wavelength. It is pointed out that for the commonest method of solving integral equations numerically (the method of subsections), the accuracy depends strongly on the position in each subsection of the point to which the field is referred. The dependence of the error on position is examined quantitatively.
6 citations
TL;DR: In this article, the equivalence between Sommerfeld's formulation for an oscillating dipole and the result based on the dyadic Green function technique was shown, and the complication resulting from the use of the set of the longitudinal vector wave functions in formulating electromagnetic problems was also pointed out.
Abstract: The authors call attention to the equivalence between Sommerfeld's formulation for an oscillating dipole and the result based on the dyadic Green function technique. The complication resulting from the use of the set of the longitudinal vector wave functions in formulating electromagnetic problems is also pointed out
TL;DR: In this paper, an approximate solution for two-dimensional problems of electromagnetic fields in the presence of cylindrical objects has been found by approximate evaluation of a scattering matrix, where the equations are derived for arbitrary physical properties and cross sections and a procedure for evaluation of the matrix elements is discussed.
Abstract: Approximate solutions for two-dimensional problems of electromagnetic fields in the presence of cylindrical objects have been found by approximate evaluation of a scattering matrix The equations are derived for cylindrical objects of arbitrary physical properties and cross sections and a procedure for evaluation of the matrix elements is discussed The elements of permittivity and permeability tensors are assumed to be analytic, but otherwise arbitrary functions of the transverse coordinates
TL;DR: In this article, a coupled thermal and electromagnetic modeling of hyperthermia in biological tissues is presented, where the thermal processes within the tissues are predicted by using a steady-state bio-heat transfer equation.
Abstract: A coupled thermal and electromagnetic modeling of hyperthermia in biological tissues is presented. The thermal processes within the tissues are predicted by using a steady-state bio-heat transfer equation. The rate of volumetric heat generation within the tissues during the passage of microwave irradiation is obtained after solving Maxwell's field equations. All the governing equations have been solved by the finite element method, using C -continuity, threenoded isoparametric elements. The numerical solutions have been validated by comparing with the analytical solutions for a simplified case. Finally, we present the temperature distributions for a real case. The effect of perfusion has been highlighted. Tumor with little blood flow rate shows good therapeutic advantage during hyperthermical irradiation.
TL;DR: In this article, the diffraction of an electromagnetic wave by a fiber bundle is studied using a dynamical theory, and a system of linear differential equations of second order is obtained, with the Fourier coefficients of the electric displacement vector as unknowns.
TL;DR: In this article, a variational bound (minimum) principle originally introduced in quantum mechanical scattering problems is adapted to the scattering of electromagnetic waves by a nonsymmetric obstacle in a rectangular waveguide.
Abstract: A variational bound (minimum) principle originally introduced in quantum mechanical scattering problems is here adapted to the scattering of electromagnetic waves by a nonsymmetric obstacle in a rectangular waveguide. Numerical results are given for a simple case.
01 May 1970
TL;DR: Numerical evaluation of Kirchhoff-Kottler formulation of electromagnetic field backscatter and application to antenna surfaces is presented in this paper, where the authors consider the application of backscattering on antenna surfaces.
Abstract: Numerical evaluation of Kirchhoff-Kottler formulation of electromagnetic field backscatter and application to antenna surfaces
01 Sep 1970
TL;DR: In this article, the authors developed numerical procedures for the digital solution of integral equations for the currents induced in a perfectly conducting, two dimensional periodic surface when a plane electromagnetic wave is incident.
Abstract: : Numerical procedures are developed for the digital solution of the integral equations for the currents induced in a perfectly conducting, two dimensional periodic surface when a plane electromagnetic wave is incident. Data are obtained for the surface and far fields for a variety of sinusoidal surfaces for plane waves of either polarization at oblique as well as normal incidence, and the results are compared with the predictions of physical optics.
01 Jan 1970
16 Sep 1970
01 Jan 1970
TL;DR: Matrix multidimensional singular linear integral equation applied to electromagnetic radiation transfer through stratified atmosphere as mentioned in this paper was used to transfer electromagnetic radiation through a stratified environment. But it is not suitable for the application in space.
Abstract: Matrix multidimensional singular linear integral equation applied to electromagnetic radiation transfer through stratified atmosphere
TL;DR: In this article, a system of differential equations is given for the sublimation subject to an integral flux of electromagnetic energy; results are given from an experimental test of the solution to a simplified form of this system.
Abstract: A system of differential equations is given for the sublimation subject to an integral flux of electromagnetic energy; results are given from an experimental test of the solution to a simplified form of this system.