Study of Electromagnetic Radiation Sources Using Time Reversal: Application to a Power Electronic Converter

Recently, modern power electronic systems have been introduced in different applications, such as in avionics and wireless communication. The increasing technological complexity of these systems is posing serious challenges regarding electromagnetic compatibility (EMC) issues. Indeed, the radiation emitted from electronic circuits can induce harmful effects on nearby devices. Thus, several research works have been conducted using the nearfield technique to deal with electromagnetic interferences (EMI) that might occur, especially due to rapidly changing currents and voltages. In the present work, a detailed study about the characterization of the electromagnetic nearfield-radiated emissions is established using a time-domain analysis to provide an equivalent model constituted of a set of electromagnetic dipole parameters. Source reconstruction has been obtained using electromagnetic time reversal (EMTR), which has proven successful and efficient in identifying transient disturbance sources in power electronics. Experimental measurements of the magnetic nearfield have been carried out under an AC/DC flyback converter. The accuracy of the proposed method has been confirmed by visualizing measured magnetic field components, which are in good agreement with the calculated maps. The results of a reasonable computing time have shown that, particularly in transient signals with a wide frequency band, the suggested inverse method is an adequate alternative to overcome frequency domain limitations.

The calculation of the field of an antenna located near the human head

In this work, a numerical calculation was carried out in one of the universal programs for automatic electro-dynamic design. The calculation is aimed at obtaining numerical values for specific absorbed power (SAR). It is the SAR value that can be used to determine the effect of the antenna of a wireless device on biological objects; the dipole parameters will be selected for GSM1800. Investigation of the influence of distance to a cell phone on radiation shows that absorbed in the head of a person the effect of electromagnetic radiation on the brain decreases by three times this is a very important result the SAR value has decreased by almost three times it is acceptable results.

Model and Simulation of the Brain Scalp Potential Analysis

Based on spherical head models, this paper, by employing the finite element method (FEM), analyzes the potential distribution of the brain scalp surface and attempts to work out the electroencephalography (EEG) forward problem, in hope of finding out the impact the dipole parameters has on it. According to the electromagnetism theory, this paper discusses the general resolution of EEG, it requires electric potentials of the globe's surface, and graphically displays results of computation through finite element post-processing, which tests their effectiveness. Furthermore, it analyzes the influences of dipole parameters on the potential distribution of scalp surface, such as position, direction and strength, which attempts to provide an effective method to solve EEG forward problem, based on diversified head model, and also proposes a prior information to the solution to EEG inverse problem.