Véronique Beauvois

An FETD approach for the modeling of antennas

In this paper an implicit Finite Element Time Domain (FETD) method is applied to the computation of the electromagnetic fields emitted by a commercial broadband log periodic antenna. The method is based on a Whitney edge finite element scheme for the space discretization together with a Newmark algorithm and a Krylov solver for the time integration. Global antenna performances are deduced thanks to a discrete Fourier transform and a boundary element extrapolation, and are compared with experimental data.

In situ testing of large machines: Alternative methods for conducted emission measurements

On the legal aspect, the new European Directive on ElectroMagnetic Compatibility 2004/108/EC concerns also large machines. On a technical point of view, the special situation to characterise the EMC behaviour of large machines imply that current procedures are complex and very expensive, and in some cases even not possible. Adapted measuring methodologies and procedures are needed. As a response to this situation and within the European R&D Frameworks, the TEMCA2 project aimed to develop new and adapted methodologies for the assessment of EMC related to this type of industrial large machinery.

On calibration of correction law for EMF measurement errors due to the proximity of the human body

We present in this paper the calibration of a correction law to overcome the electric field (e-field) measurement errors due to the presence of the dosimeter in the vicinity of the human body. The Correction law proposes to use only two measuring points close to the body. These measurements are made at regularly goshawks separate points of the body, either in the chest, abdomen or waist. The goal is to propose a useful distributed worn-body dosimeter who can apply a correction law to these separate values compared to the maximum value known beforehand. This correction law is currently derived to simulation for GSM, DCS and UMTS downlink Bands and shortly performed by measurements. Assessing the real EMF exposure value in real-time is the key question for sanitary authorities as well as for industry (Manufacturer and Operator).

An Indirect Alternative Method of Measurement for Conducted Emissions of High-Power Equipments

This paper deals with a novel indirect measurement method using a “virtual” LISN to get normalised, reproducible and accurate results. According to the CISPR 16-2-1 standard [1], in the low frequency range, conducted emission measurements should be performed on power supply lines either with a Line Impedance Stabilized Network (LISN) or with a passive voltage probe. However both methods have drawbacks in terms of accuracy, feasibility, etc. This paper briefly compares different direct alternative methods of conductive emission measurement in case of high-power equipements. Furthermore, a new indirect method of measurement based on the research of a simple and stable EUT model and using a “virtual” LISN is presented.

Measurement Methodologies for Reducing Errors in the Assessment of EMF by Exposimeter

Objective: As well known, using a single body worn sensor exposimeter introduces systematic errors on the measurement of the incident free space electric field strength. This is because the body creates around it high, intermediate and low level field zones, which depend on the direction of arrival of the incident field. The goal of this work is to propose an efficient method for the reduction of these errors. Methods: After classifying the perturbations induced by the body on the measured electric and magnetic fields thanks to realistic numerical simulations, we then propose a two-sensor setup in conjunction with simple semi-empirical correction formulas, in order to compensate these perturbations. Results: At 942 MHz, when the two sensors are placed in any opposite sides of the body at chest height, the worst case, maximum and average errors respectively decrease to 12% and 3% compared to 83% and 22% for measurement techniques using a single sensor, or 32% and 11% when using the average value of the measurements. Conclusion: The error related to the measurement in the presence of the body was significantly reduced by the proposed method making use of two opposite sensors, E-field and H-field at the chest. Significance: The conformity of exposure to EMF in terms of reference values according to the ICNIRP is given in the abscence of the human body. The interest of this work lies in the reduction of the errors made when measuring the field in the presence of the body.

Experimental Correction of Radiation Patterns Between Electromagnetic Environments

This paper presents an experimental method to estimate a radiation pattern obtained in a particular echoic environment (for example, from in situ measurements) as if measurements were performed in a given anechoic chamber. The correction is achieved using some reference measurements collected both in echoic and anechoic environments. An angular transfer function is estimated from these two sets of measurements and deconvolved from the measured radiation pattern to be corrected.