Limoges, France
Limoges, France
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Essaidi N.,University of Limoges | Nadir H.,University of Limoges | Martinod E.,University of Limoges | Feix N.,University of Limoges | And 4 more authors.
Journal of the European Ceramic Society | Year: 2017

Due to their interesting properties, geopolymers have found various applications in different domains. The evaluation of the dielectric properties of a geopolymer matrix for RF applications is innovative. In this context, this paper focuses, first, on the evaluation of the suitability of a geopolymer matrix with dielectric materials, and then on the improvement of the real permittivity value of the obtained material. For this purpose, the precursors either dielectric powder or aluminosilicate powder were first characterized. Then, the feasibility of the geopolymer matrix was investigated. Based on the feasibility test, it was shown that these kinds of materials can be successfully filled with various types of dielectric materials, such as ZrO2, BaTiO3 and Y2O3. Moreover, the optimized parameters of the synthesis process, which included a small amount of water in the formulation, were 20 °C for the synthesis temperature, 85% for the humidity level and 7 days for the setting time. The measurement of the dielectric properties evidenced, first, that the real part of the relative permittivity strongly depends on the formulation and storage process. Then, the incorporation of a high percentage of BaTiO3 (60%) induced an increase in the real part of the permittivity value and a decrease in the loss tangent. Finally, the mixing law of Maxwell-Garnet was applied to compare the theoretical and measured values of the permittivity. It was deduced that the small difference detected at low percentages whatever the dielectric materials can be explained by the preponderant effect of the geopolymer matrix compared to ZrO2 or BaTiO3, it seems that the mixing law well functioned with BaTiO3 than ZrO2. This is in accordance with the better dielectric properties for samples containing BaTiO3. © 2017 Elsevier Ltd

Fezai F.,French National Center for Scientific Research | Menudier C.,University of Limoges | Thevenot M.,CNRS XLIM Research Institute, Limoges | Vollaire C.,École Centrale Lyon | And 2 more authors.
IEEE Antennas and Propagation Magazine | Year: 2016

In this article, we use a conversion chain to minimize standby-mode power consumption, detailing the different parts of the emitter and the receiver. The proposed technology is based on an efficient radio-frequency (RF) energy transfer and an RF-dc conversion circuit with a self-maintained switch that wakes up an electronic device [e.g., television (TV), home automation systems, etc.], using an integrated emitter and a receiver with performances suitable for home or industrial applications. The developed system works in the industrial, scientific, and medical (ISM) band (2.4-2.48 GHz). © 1990-2011 IEEE.

Desrumaux L.,XLIM OSA | Godard A.,XLIM OSA | Lalande M.,XLIM OSA | Bertrand V.,CISTEME | And 2 more authors.
IEEE Transactions on Antennas and Propagation | Year: 2010

A novel ultrawideband (UWB) antenna, called the Shark antenna, and designed especially for transient applications is proposed in this paper. A Shark antenna array is also conceived in order to obtain a high power UWB pulse radiation source through the frequency band [800 MHz-8 GHz]. For this application, the elementary antenna must be compact, non-dispersive, and the array must have a high transient front to back ratio. The geometry of the Shark antenna and its radiation characteristics are detailed. Moreover, an approach which evaluates the transient front to back ratio of a square array is presented. © 2006 IEEE.

Arnaud E.,Faculte des science et Techniques | Chantalat R.,CISTEME | Monediere T.,Faculte des science et Techniques | Rodes E.,Faculte des science et Techniques | Thevenot M.,Faculte des science et Techniques
IEEE Antennas and Wireless Propagation Letters | Year: 2010

This letter presents an original solution to solve the matching problem of the circularly self-polarizing electromagnetic band-gap (EBG) antennas. More precisely, a comprehensive method to design a self-polarizing EBG antenna will be detailed. This kind of antenna had been designed before, but it was very poorly matched. An iris-based matching system has been used here, which produced a satisfying return loss while deteriorating the axial ratio (AR). An original device will be introduced, which allowed us to compensate for this degradation. Finally, to validate this new structure, a 20-dBi antenna working around 9 GHz and showing an AR lower than 1 dB over a 100-MHz bandwidth has been conceived, realized, and successfully measured. © 2006 IEEE.

Yahiaoui R.,University of Limoges | Chantalat R.,CISTEME | Chevalier N.,CISTEME | Jouvet M.,University of Limoges | Lalande M.,University of Limoges
Progress In Electromagnetics Research C | Year: 2013

We report the numerical and experimental investigation of a highly directive Fabry-Pérot (FP) cavity antenna based on a metamaterial, operating in the microwave regime. Numerical simulations using finite element method and reflection-transmission microwave measurements have been performed and a good quantitative agreement has been observed. Measured return losses and radiations patterns done in an anechoic chamber agree very well with the simulated ones. The potential application of the proposed FP cavity antenna in a non-contact breathing sensor is proposed and evaluated. Experimental record and frequency spectrum for respiratory movements of human-being (voluntary under test) are presented. The low cost and simple fabrication process of the proposed FP cavity antenna make it very promising for its integration in modern telecommunication systems.

Zhang H.,French National Center for Scientific Research | Abdallah Y.,French National Center for Scientific Research | Chantalat R.,CISTEME | Thevenot M.,French National Center for Scientific Research | And 2 more authors.
IEEE Antennas and Wireless Propagation Letters | Year: 2012

This letter presents the design of a low-profile, high-gain Yagi wire-patch antenna array that radiates a directional beam in the azimuthal plane within the frequency band 5.45-5.75 GHz. The elementary unit of a typical Yagi antenna is replaced by wire-patch antenna. This antenna delivers a gain of 14.8 dB at 5.6 GHz. A prototype of this modelized antenna is manufactured, and the measured performances are similar to the simulated ones. © 2012 IEEE.

Hajj M.,French National Center for Scientific Research | Chantalat R.,CISTEME | Monediere T.,French National Center for Scientific Research | Jecko B.,French National Center for Scientific Research
IEEE Antennas and Wireless Propagation Letters | Year: 2010

In this letter, a novel sectoral antenna for 45° linear polarization with a high improved isolation and low cross polarization using metallic electromagnetic band-gap (M-EBG) material is investigated. This antenna provides two orthogonal polarizations, vertical and horizontal, 45° with a sectoral radiation pattern in the azimuth plane. In order to verify the results, a dual polarized M-EBG sectoral antenna prototype for WiMAX [5.15-5.35] GHz application is realized and measured. Finally, the possibility to generate 45° linear polarization is studied. © 2006 IEEE.

Toubet M.S.,XLIM | Chantalat R.,XLIM | Hajj M.,CISTEME | Jecko B.,CISTEME | Diot J.C.,CEA Cesta
Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012 | Year: 2012

In this paper, we present a Wide Bandwidth (71%), ultra Low-Profile (<λ/10) and High-Gain (17 dB) EBG antenna which is used for high power and electronic warfare applications. A prototype of this modelized antenna is manufactured and the measured performances are compared to the simulated ones. © 2012 IEEE.

Desrumaux L.,XLIM OSA | Lalande M.,XLIM OSA | Andrieu J.,XLIM OSA | Bertrand V.,CISTEME | Jecko B.,XLIM OSA
Progress In Electromagnetics Research B | Year: 2011

An innovative radar imaging system, based on the capability of a fixed UWB array to radiate short pulses in different directions along time with the principle of electronic beam steering, is presented in this paper. To demonstrate its concept, the analysis presented in this paper is based on simulation results. As function of the use of either only one antenna or several antennas in reception, two radar imaging algorithms have been developed and are detailed in this paper. These algorithms permit to obtain an image of the analyzed scene thanks to the transient beam pattern of the array used in emission. Finally, with a same analyzed scene, these algorithms have been compared with the time reversal method and the back projection algorithm, in association with a SAR imaging system. The conditions of applicability of these methods are also discussed.

Troubat M.,France Paratonnerres | Barriere F.,France Paratonnerres | Perrin E.,CISTEME
2012 31st International Conference on Lightning Protection, ICLP 2012 | Year: 2012

This paper proposes a new method to reduce and control the electromagnetic field due to a lightning current flowing down the down-conductors around a structure. The influence of the number of down-conductors and the earthing resistance value on the radiated field is studied thanks to a parametric study. © 2012 IEEE.

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