Bernard Bayard - Academia.edu (original) (raw)

Papers by Bernard Bayard

$Research paper thumbnail of Characterization of the refractive index of isotropic materials by three-detector microwave ellipsometry$

International Journal of Innovation and Applied Studies, 2019

A three-detector microwave ellipsometer is an experimental free-space bench for characterization ... more A three-detector microwave ellipsometer is an experimental free-space bench for characterization of non-transparent materials. It is a non-destructive characterization technic working in oblique transmission in the frequencies range of 26 to 30 GHz. A vector network analyzer (VNA) is used as microwave source. The method is based on the determination of complex diagonal tensor which requires the measurement of the sample transmission coefficients. Calibration of the network vector analyzer is needed in order to correct the values of this coefficients due to the measurement errors. The aim of this paper is to show that One Path Two Ports calibration method is convenient for this technic.

Apres une presentation sommaire des enjeux et motivations relatifs a la generation de jets photon... more Apres une presentation sommaire des enjeux et motivations relatifs a la generation de jets photoniques, ce papier se propose de presenter une nouvelle structure guidee permettant d'obtenir de fortes concentrations energetiques. Afin d'en preciser l'interet, nous nous proposons de relater les resultats actuellement disponibles dans la litterature [1-2]. La modelisation numerique a ete realisee par l'utilisation de plusieurs methodes numeriques, en particulier la Methode Modale de Fourier (FMM) [3] et la Methode modale basee sur les polynomes de Gegenbauer (MMGE) [4]. Nous souhaitons apres avoir valide les resultats lors d'une confrontation avec un prototype experimental, utiliser ce modele dans le cadre d'une detection en champs proches a travers des structures opaques.

IEEE Transactions on Electromagnetic Compatibility, 2021

Electromagnetic shielding properties of cables can be characterized by transfer impedance and pla... more Electromagnetic shielding properties of cables can be characterized by transfer impedance and planar shields by shielding effectiveness. Both properties are associated with measurement techniques, which have their own frequency limitations. The concept of sheet transfer impedance is proposed to allow the transition of complex cylindrical structures to planar configurations through a simple and efficient formula. Three-dimensional full-wave simulations of the periodic pattern of plate shields and planar braid shields are performed and compared to cylindrical analytic models. The proposed formula is validated by a good concordance between shielding effectiveness and transfer impedance values. Consequently, the industrial qualification tools such as transfer impedance and shielding effectiveness can then be linked to each other, and the two techniques can be used complementarily to cover a wide frequency range. Moreover, complex cylindrical structures can be more easily simulated using planar periodic patterns.

IEEE Transactions on Electromagnetic Compatibility, 2020

Metal textile fabrics used in electromagnetic shielding are often complex structures, and manufac... more Metal textile fabrics used in electromagnetic shielding are often complex structures, and manufacturers need approximate models to predict their performance. In addition, different physical phenomena make their behavior varying according to the frequency bands. We propose to develop a model to determine the response of these materials in different frequency bands, and this article presents the low-frequency part of the model. A simple method of modeling braids and metallic grids at low frequency is proposed. Because of their periodic nature, these textile structures can be reduced to an elementary pattern that constitutes them. The calculus of the shielding effectiveness (SE) is then possible for complex structures. The concept of sheet transfer impedance has been defined to allow the passage of complex cylindrical structures to planar forms through a simple and efficient formula. The industrial qualification tools such as transfer impedance and SE can then be linked to each other. Full-wave three-dimensional simulations of periodic pattern of braids and grids show a very good agreement (around 0.1 dB) with the proposed analytical model in the lowfrequency band up to 100 kHz and an acceptable approximation up to 1 MHz.

IEEE Transactions on Microwave Theory and Techniques, 2005

physica status solidi (c), 2004

An issue of current research is the integration of microwave ferrite devices with semiconductor t... more An issue of current research is the integration of microwave ferrite devices with semiconductor technologies by using vacuum deposition techniques. Thin magnetic films may be used in commercial products and they can be more easily involved in the development of magnetic devices if we are able to extract their magnetic properties. One of the interesting points of this paper is to highlight the properties of a thin film, such as anisotropic behavior to release non reciprocal devices. A study of physicochemical and magnetic properties is tackled and experimental results are discussed. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

IEEE Transactions on Microwave Theory and Techniques

Progress In Electromagnetics Research Letters, 2016

The aim of this work is to characterize the electrical conductivity of composite conductors depos... more The aim of this work is to characterize the electrical conductivity of composite conductors deposited on an alumina substrate. Several half-wavelength coplanar resonators are realized using several pure conductors, silver (Ag), copper (Cu), gold (Au) and tin (Sn), to compare their quality factors (Q 0), related to losses, with those from analytical methods. In the literature, losses in coplanar components have been estimated by different analytical methods. We have put in evidence the relationship between electrical conductivity of the conductor and the resonator quality factor. An overall good agreement among quality factor values obtained by the analytical formulas, by numerical simulations and by microwave measurements is observed. The surface roughness is taken into account to better estimate real conductor losses. Therefore, these analytical formulas are used to extract the electrical conductivity values of the composite conductors (Ag-aC, AgSnIn and AgSn), from measured quality factors.

J Phys Iv, 2005

Some microwave passive components (such as circulators, isolators, ... etc) still use bulk magnet... more Some microwave passive components (such as circulators, isolators, ... etc) still use bulk magnetic materials. A method for the dielectric and magnetic characterization of multi-layer materials in the microwave range is presented as well as its reliability and its domain of validity. It allows to determine the elements of the permeability tensor of gyromagnetic slab. This method of material characterization can be implemented at various microwave bands by changing the geometrical dimensions of the rectangular waveguide.

International Journal of Online Engineering, Feb 4, 2009

ABSTRACT

Progress in Electromagnetics Research C, Feb 1, 2011

The planar metal particles, consisting of a multi-turn spirals, are studied with the aim of using... more The planar metal particles, consisting of a multi-turn spirals, are studied with the aim of using them to realize high impedance surfaces or as an elementary cell to create an artificial material. These spirals present a resonant behaviour in a certain frequency band. To obtain miniature devices, a compromise between the surface and the efficiency of the resonance must be found. The compactness of the particles can be increased by using s spirals. However, the accuracy on resonant frequency of existing models is not sufficient for our applications. We present a simple analytical model that determines the resonant frequency from the geometric dimensions of the approximated model. This model is verified by electromagnetic simulations and by measurements.