Showing papers on "Computational electromagnetics published in 1972"
TL;DR: The classic extinction theorem of molecular optics, due to Ewald and Oseen is generalized to scattering of an electromagnetic wave on a material medium of completely arbitrary response (constitutive relations) as discussed by the authors.
70 citations
01 Sep 1972
TL;DR: In this article, the main subjects of the report are a generalized relaxation method and a generalized inverse method for interactively solving large integral equations, specifically applicable to the k-space formulation of such integral equations.
Abstract: : The main subjects of the report are a Generalized Relaxation method and a Generalized Inverse method for interactively solving large integral equations. These methods are specifically applicable to the k-space formulation of such integral equations. The report consists of a brief development of the k- space formulation of the initial value problem, with brief treatment of the electromagnetic scattering problem as a special case; and with detailed emphasis on the development of the generalized relaxation function method and the generalized inverse method.
69 citations
TL;DR: In this article, the electromagnetic fields produced by a circular loop of current were considered for a homogeneous half-space model of the earth and integral representations for the subsurface field were evaluated numerically and presented in graphical form.
Abstract: The electromagnetic fields produced by a circular loop of current is considered for a homogeneous half-space model of the earth. The integral representations for the subsurface field are evaluated numerically and presented in graphical form.
32 citations
TL;DR: In this paper, the behavior of electromagnetic waves in irrotational moving media is studied based on Maxwell's equations and Minkowski's constitutive relations taken to the first order in the velocity.
Abstract: The behavior of electromagnetic waves in irrotational moving media is studied. The model is based on Maxwell's equations and Minkowski's constitutive relations taken to the first order in the velocity. Accordingly, the effect of acceleration on the electromagnetic fields is neglected. The new velocity effects are investigated by considering simple propagation and scattering problems: scattering in the presence of fluid sources and boundaries, rotating media and a uniform flow perturbed by the presence of a circular cylinder and a sphere.
12 citations
11 citations
01 Jan 1972
10 citations
TL;DR: In this article, a point-like relativistic spinning particle in an external electromagnetic field is derived and the equations are non-linear with singular points appearing when the field is higher than a critical value, and an analogy is suggested between this and the noncausal propagation of solutions of quantum equations for high spins in external fields.
Abstract: Equations of motion are derived for a pointlike relativistic spinning particle in an external electromagnetic field, neglecting radiative and quantum corrections. The equations are non-linear with singular points appearing when the field is higher than a critical value. An analogy is suggested between this and the noncausal propagation of solutions of quantum equations for high spins in external fields.
10 citations
TL;DR: In this paper, the field scattered by an ungrounded conducting sphere above a ground plane is considered and the quasi-static solution is facilitated by the use of bispherical coordinates.
Abstract: The field scattered by an ungrounded conducting sphere above a ground plane is considered. The quasi-static solution is facilitated by the use of bispherical coordinates. The approximate solution obtained by considering only the interaction of dipole modes with the interface is presented for comparison. The general results are used to calculate the backscatter of a low frequency ground wave by a small obstacle.
7 citations
01 Apr 1972
TL;DR: In this article, the authors developed numerical procedures for the digital solution of the integral equations for the current induced on a perfectly conducting, two-dimensional periodic surface of arbitrary profile when a plane electromagnetic wave is incident by using Floquet's theorem.
Abstract: : Numerical procedures are developed for the digital solution of the integral equations for the current induced on a perfectly conducting, two- dimensional periodic surface of arbitrary profile when a plane electromagnetic wave is incident By using Floquet's theorem the range of integration is reduced to a single period, and special summation techniques consisting of a Poisson summation and the subtraction of the dc term are used to improve the convergence of the infinite series representation of the Green's function The integral equations are then solved numerically using the moment method and an interpolation scheme Data are obtained for both the surface and far fields for a variety of sinusoidal, full-wave rectified, inverted full-wave rectified and triangular profiles for plane waves of either polarization at oblique as well as normal incidence, and the results are compared with the predictions of physical optics
4 citations
TL;DR: In this paper, the minimal electromagnetic interaction is introduced into various free, quantum mechanical spin one formalisms, and it is found that the resulting theories are essentially equivalent for simple such interactions in one formalism are found, in general, to be equivalent to structurally more complicated interactions in the other formalisms considered.
Abstract: The minimal electromagnetic interaction is introduced into various free, quantum mechanical spin one formalisms, and it is found that the resulting theories are essentially equivalent. The situation does not prevail when, in addition, magnetic dipole or electric quadrupole interactions are considered. For simple such interactions in one formalism are found, in general, to be equivalent to structurally more complicated interactions in the other formalisms considered. Some known results on the acausal propagation of solutions of wave equations for a classical spin one particle in an external electromagnetic field are, with the aid of the above equivalence theorems, which are easily seen to apply to the classical case also, extended to include all the spin one formalisms considered herein.
01 Jan 1972
01 Dec 1972
01 Aug 1972
TL;DR: A brief survey of recent theoretical progress on the inverse scattering problem for radiation scattering from reflective boundaries and variable indices of refraction can be found in this article, with a focus on far-field relations between incident and scattered radiation in the presence of a scattering object.
Abstract: A brief survey of recent theoretical progress on the inverse scattering problem for radiation scattering from reflective boundaries and variable indices of refraction. The theory of radiation scattering is concerned primarily with the far-field relations between incident and scattered radiation in the presence of a scattering object. The primary, or direct, problem of this theory is to develop quantitative information about these scattering relations from a knowledge of the scattering object. The secondary, or inverse, problem, on the other hand, is to determine the nature of the object from an analysis of the scattering relations.
TL;DR: In this paper, it was shown that there exist spin-two Lagrangians which yield equations of motion that are stable as far as the number of degrees of freedom is concerned when electromagnetic interaction is introduced via minimal replacement.
Abstract: During the last couple of years, VRLO and ZWANZIGER (1) have investigated the problems arising in the interaction of higher-spin particles interacting with the electromagnetic field via minimal interaction. In particular, for spin-two particles, one of the results that emerge from their work is that the number of degrees of freedom of a spin-two particle interacting with an electromagnetic field increases to six, which is one more than in the free-field case. This result is already contained implicitly in an earlier paper by ~:EDERBUSH (2) who also suggested the use of nonmiuimal terms in the interaction to recover the correct number of degrees of freedom. The purpose of this note is to show that there exist spin-two Lagrangians which yield equations of motion that are stable as far as the number of degrees of freedom is concerned when electromagnetic interaction is introduced via minimal replacement. A similar result has already been pointed out by HAGEN (a) in the context of linearized Lagrangians. We, however, work with the second-order formalism. We start by writing the free spin-two Lagrangian considered by VELO and ZWANZIGF~R (1) ;
01 Jan 1972
TL;DR: In this paper, a solution to the scattering problem of a pulse incident on a low-density dielectric sphere is presented, where pulse modulated harmonic carriers and dc pulses are considered.
Abstract: The solution to the scattering problem of a pulse incident on a low-density dielectric sphere is presented. Pulse modulated harmonic carriers and dc pulses are considered.
01 Dec 1972
TL;DR: In this paper, the propagation of modes in an idealized model of the earth-crust waveguide is considered, and the excitation factor for the structure is derived for voltage-type and electric, current line sources.
Abstract: Propagation of modes in an idealized model of the earth-crust waveguide is considered. The two-layer region is bounded above and below by a perfectly conducting plane. For this structure, there are an infinite number of discrete modes without any contribution from a continuous spectrum. The excitation factor for the structure is derived for voltage-type and electric, current line sources. Specific numerical results for 1 to 1000 Hz are given for the case where the lower conductive region is effectively of infinite depth. It is found that the conductivity of the upper region is the main controlling factor on the attenuation rate.
01 Feb 1972
TL;DR: In this article, it is shown how the first one or two terms in the far zone scattered fields can be expressed in terms of quantities which are functions only of the geometry of the body each of these is the weighted integral of an elementary potential function which can be found by solving an integral equation.
Abstract: : The low frequency scattering of electromagnetic and acoustic waves by rotationally symmetric bodies is considered By concentrating on certain quantities such as the normalised component of the induced electric and magnetic dipole moments, it is shown how the first one or two terms in the far zone scattered fields can be expressed in terms of quantities which are functions only of the geometry of the body Each of these is the weighted integral of an elementary potential function which can be found by solving an integral equation A computer program has been written to solve the appropriate equations by the moment method, and for calculating the dipole moments, the electrostatic capacity, and a further quantity related to the capacity The program is described and related data are presented
01 Jan 1972