scholarly journals Electromagnetic Interference between Cranes and Broadcasting Antennas

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
V. Javor
Keyword(s):  
Electromagnetic Field ◽  
Electromagnetic Interference ◽  
Wire Antenna ◽  
Directional Characteristic ◽  
Interesting Phenomenon ◽  
Point Matching ◽  
Electrical Shock ◽  
Burning Pain ◽  
Induced Currents ◽  
Transmitting Antenna

An interesting phenomenon was noticed in some cases by workers operating with cranes in electromagnetic field of broadcasting antennas. They experienced electrical shock or burning pain at distances of kilometers away from powerful transmitters because cranes act as unintentional receiving antennas. The solution to this problem depends on dimensions and positioning of the crane structure, electromagnetic field strength at the site, frequency, and directional characteristic of the transmitting antenna. Electromagnetic interference between such structures is analyzed in this paper. Computational results for the induced currents and voltages in crane, treated as wire antenna problem, are determined using integrodifferential equations for the current along conductive structure, satisfying boundary condition for the electric field. Point matching method as the Method of Moments (MoM) is applied for solving these equations and polynomial approximation of the current is used. Results are presented for different crane structures and possible solutions to this problem are given.

scholarly journals Closed-Form Expressions for Numerical Evaluation of Self-Impedance Terms Involved on Wire Antenna Analysis by the Method of Moments

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1316
Author(s):  
Carlos-Ivan Paez-Rueda ◽  
Arturo Fajardo ◽  
Manuel Pérez ◽  
Gabriel Perilla
Keyword(s):  
Numerical Integration ◽  
Method Of Moments ◽  
Computing Time ◽  
Basis Functions ◽  
Wire Antenna ◽  
Complex Geometries ◽  
Point Matching ◽  
Piecewise Constant ◽  
Matching Procedure ◽  
Time Required

This paper proposes new closed expressions of self-impedance using the Method of Moments with the Point Matching Procedure and piecewise constant and linear basis functions in different configurations, which allow saving computing time for the solution of wire antennas with complex geometries. The new expressions have complexity O(1) with well-defined theoretical bound errors. They were compared with an adaptive numerical integration. We obtain an accuracy between 7 and 16 digits depending on the chosen basis function and segmentation used. Besides, the computing time involved in the calculation of the self-impedance terms was evaluated and compared with the time required by the adaptative quadrature integration solution of the same problem. Expressions have a run-time bounded between 50 and 200 times faster than an adaptive numerical integration assuming full computation of all constant of the expressions.

scholarly journals On the transfer of energy in the electromagnetic field

1883 ◽  
Vol 36 (228-231) ◽  
pp. 186-187
Keyword(s):  
Electromagnetic Field ◽  
Magnetic Permeability ◽  
Surrounding Medium ◽  
Primary Circuit ◽  
Electric Currents ◽  
Electromagnetic Forces ◽  
Induced Currents ◽  
Point To Point ◽  
Work Done ◽  
A Current

A space containing electric currents may be regarded as a field where energy is transform ed a t certain points into the electric and magnetic kinds by means of batteries, dynamos, thermoelectric actions, and so on, while in other parts of the field this energy is again transformed into heat, work done by electromagnetic forces, or any form of energy yielded by currents. Formerly a current was regarded as something travelling along a conductor, attention being chiefly directed to the conductor, and the energy which appeared at any part of the circuit, if considered at all, was supposed to be conveyed thither through the conductor by the current. But the existence of induced currents and of electromagnetic actions at a distance from a primary circuit from which they draw their energy, have led us, under the guidance of Faraday and Maxwell, to look upon the medium surrounding the conductor as playing a very important part in the development of the phenomena. If we believe in the continuity of the motion of energy, that is, if we believe that when it disappears at one point and reappears at another, it must have passed through the intervening space, we are forced .to conclude that the surrounding medium contains at least a part of the energy, and that it is capable of transferring it from point to point. Upon this basis Maxwell has investigated what energy is contained in the medium, and. he has given expressions which assign to each art of the field a quantity of energy depending on the electromotive and magnetic intensities, and on the nature of the matter at that part l regard to its specific inductive capacity and magnetic permeability. These expressions account, as far as we know, for the whole energy. According to Maxwell’s theory currents consist essentially in a certain distribution of energy in and around a conductor, accompanied by transformation and consequent movement of energy through the field.

scholarly journals Power Constrained Space-Time Processing for Suppression of Electromagnetic Fields

2017 ◽  
Vol 1 (1) ◽  
pp. 71 ◽  
Author(s):  
Tommy Hult ◽  
Abbas Mohammed
Keyword(s):  
Electromagnetic Field ◽  
Power Density ◽  
Active Control ◽  
Mimo System ◽  
Superposition Principle ◽  
Human Head ◽  
Antenna System ◽  
Space Time ◽  
Time Processing ◽  
Transmitting Antenna

Active suppression of noise and vibrations is a well established field of research with many applications in acoustic and mechanical industries. In this paper we investigate the possibility of applying these adaptive active control methods with the aim of lowering the electromagnetic power density at a specific volume in space using the superposition principle and space-time processing employing the full MIMO (Multiple Input Multiple Output) antenna system setup. The application that we evaluated is a model of a mobile phone equipped with one ordinary transmitting antenna and two actuator-antennas whichpurpose is to cancel out the electromagnetic field at the human head while maintaining a predefined level of the overall output power of the system. This power control is achieved through the use of a quadratic constraint on the active control algorithm. Simulation results show the promise of using the adaptive control algorithms and MIMO system to attenuate the electromagnetic field power density.

scholarly journals Analysis of Omni-directivity Error of Electromagnetic Field Probe using Isotropic Antenna

2016 ◽  
Vol 16 (6) ◽  
pp. 287-293
Author(s):  
Rene Hartansky
Keyword(s):  
Electromagnetic Field ◽  
Systematic Error ◽  
Shape Change ◽  
Mutual Arrangement ◽  
Directional Characteristic ◽  
Frequency Dependent ◽  
Directional Characteristics ◽  
Different Types

Abstract This manuscript analyzes the omni-directivity error of an electromagnetic field (EM) probe and its dependence on frequency. The global directional characteristic of a whole EM probe consists of three independent directional characteristics of EM sensors - one for each coordinate. The shape of particular directional characteristics is frequency dependent and so is the shape of the whole EM probe’s global directional characteristic. This results in systematic error induced in the measurement of EM fields. This manuscript also contains quantitative formulation of such errors caused by the shape change of directional characteristics for different types of sensors depending on frequency and their mutual arrangement.

scholarly journals Electromagnetic Field Coupling to Overhead Wire Configurations: Antenna Model versus Transmission Line Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Dragan Poljak ◽  
Khalil El Khamlichi Drissi
Keyword(s):  
Electromagnetic Field ◽  
Transmission Line ◽  
Time Domain ◽  
Unit Length ◽  
Fdtd Method ◽  
Domain Analysis ◽  
Wire Antenna ◽  
Field Coupling ◽  
The Wire ◽  
The Time Domain

The paper deals with two different approaches for the analysis of electromagnetic field coupling to finite length overhead wire: the wire antenna theory (AT) and the transmission line (TL) method. The analysis is carried out in the frequency and time domain, respectively. Within the frequency domain analysis the wire antenna formulation deals with the corresponding set of Pocklington integrodifferential equation, while the transmission line model uses the telegrapher's equations. The set of Pocklington equations is solved via the Galerkin-Bubnov scheme of the Indirect Boundary Element Method (GB-IBEM), while the telegrapher’s equations are treated using the chain matrix method and the modal equation to derive per-unit-length parameters. For the case of the time domain analysis AT model uses the space-time Hallen integral equation set, while TL approach deals with the time domain version of the telegrapher’s equations. Hallen equations are handled via time domain version of GB-IBEM, while time domain telegrapher’s equations are solved by using Finite Difference Time Domain (FDTD) method. Many illustrative computational examples for the frequency and time domain response, respectively, for several configurations of overhead wires, obtained via different approaches, are given in this paper.

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