WorldCat Identities

Kossiavas, Georges

Overview
Works: 14 works in 17 publications in 2 languages and 21 library holdings
Roles: Thesis advisor, Other, Opponent, Contributor, Author
Publication Timeline
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Most widely held works by Georges Kossiavas
Antennes microrubans polarisées par des grilles by Patrice Brachat( )

1 edition published in 1993 in French and held by 2 WorldCat member libraries worldwide

Conception, Réalisation et Caractérisation de papiers fonctionnels pour des applications de filtrage électromagnétique by Fabien de Barros( )

1 edition published in 2011 in French and held by 2 WorldCat member libraries worldwide

The electromagnetic smog in which we live today is nowadays a real issue because it limits the use of certain technologies and also because there are some potential health risks associated with it, even if the latter is still a controversial subject. The importance of the interferences between wireless networks or the possibility of data hacking on the same networks are two examples. The aim of this thesis is to develop a new way to protect buildings against some of these electromagnetic waves. More specifically, this work focuses on a technology able to filter only the WiFi and the GSM waves through large areas of a home, like a wall for example. To do this, the functionalization of a standard component of buildings, the wallpaper, was studied. The use of frequency selective surface (FSS) was chosen. These patterns are printed directly on paper with a conductive ink printing technology: the flexography. The study also focuses on the realization of innovative filter designs. Simulation results show that these novel FSS are able to filter two or three bands. They are almost insensitive to the polarization and to the angle of incidence in the range of 0° to ±80°. The realization feasibility of this concept in a laboratory or in industrial conditions was demonstrated. Next, an experimental demonstration of this concept in the WiFi bands was carried out. In this context, the transmission coefficient was reached -30 dB. Finally, an experimental validation of the product in real conditions of use was conducted, namely the wallpaper was put over plasterboards or over wood panels. Also, the influence of the glue on the general performances and the placement of a decorative wallpaper over the FSS wallpaper were studied. In conclusion, the practical results obtained confirm and validate the theoretical predictions of this new concept, called metapaper, and show that the practical realizations are efficient enough to allow the reduction of WiFi or GSM signals
Systèmes multi-antennes pour diversité et MIMO by Aliou Diallo( Book )

2 editions published in 2007 in French and held by 2 WorldCat member libraries worldwide

The high data rates required in modern communication can be achieved by multiplying the radiating element involved in the broadcast and in the reception of the wireless link. This solution is called MIMO (Multiple Input and Multiple Output). Also, to reduce the deep fading caused by the multi-path propagating environment, the diversity technique which consists to place one antenna in the broadcast and several antennas in the reception can be used. However, the integration of several efficient antennas on the printed circuit board (PCB) of a mobile phone is a new challenge for antenna researchers. The main goal remains to keep a high isolation between these radiators, otherwise, the diversity gain and the channel capacity of the system can drastically be reduced. The aim of this thesis is to demonstrate the possibility to integrate two closely spaced quarter-wavelength resonators on a small PCB, with high isolation and high total efficiencies when using a neutralization effect between the radiators. However, these two Planar Inverted-F Antennas (PIFAS) were not operating in the same frequency band (DCS and UMTS). This work has been further extended with the successful implementation of this technique to a multi-antennas system operating in the same UMTS band. Several multi-antenna handsets have been designed. Their performance in diversity and MIMO are measured in a reverberation chamber to Göteborg, and in a indoor and outdoor environments to Helsinki
Diversity Characterization of Optimized Two-Antenna Systems for UMTS Handsets by Aly Diallo( )

1 edition published in 2007 in English and held by 2 WorldCat member libraries worldwide

Radiocommunications avec les véhicules terrestres par antennes sectorielles grand gain : application aux liaisons haut débit avec les trains by Dina Serhal( Book )

2 editions published in 2009 in French and held by 2 WorldCat member libraries worldwide

This Ph.D thesis takes place in the development of land communications with mobile vehicles. In this expanding field, we developed an original model for the base station antenna within the context of the project VHDT (Very High Data-rates in Trains) in partnership with the region of Limousin and other industrial partners. The aim of this project is to provide high data rates in the trains in this region using a mobile WiMAX link between the base station and the train. The proposed antenna is an original model high gain sectoral Electromagnetic Band Gap antenna (EBG). It was wisely designed to fulfill some particular requirements that we have developed from a comprehensive study of the link considered in the project. On the other hand, we studied the link budget between the base station and the train taking into account the ground reflection of the field on the in unfavorable conditions. In this context, several solutions were proposed in order to improve and optimize the communication system
Miniaturisation et intégration d'antennes imprimées pour systèmes communicants ULB pulsés by Ali Chami( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

Cette thèse a fait partie du projet MIMOC (Méthodes d'Intégration et de Miniaturisation d'Objets Communicants) qui a été mené à terme en partenariat avec le laboratoire IM2NP de Marseille, la société InsightSIP à Sophia Antipolis et Orange Labs La Turbie. Le projet cible les systèmes de transmission par impulsions occupant une très large bande de fréquences (signaux Ultra Large Bande : ULB). Au sein de ce projet, les travaux de cette thèse ont été concentrés sur le développement, la miniaturisation et l'intégration des antennes dans des systèmes de communications ULB conformes aux normes américaines (FCC : .1-10.6 GHz) et Européennes (ECC : 6-8.5 GHz). Le développement d'une antenne consiste à en maîtriser les différents paramètres en analysant leurs influences sur l'adaptation et le rayonnement de celle-ci. Une étude préliminaire a permis de créer une base de données qui a été utilisée par la suite dans les différentes phases du projet afin de réadapter l'élément en fonction de l'évolution de son environnement. Un élément rayonnant imprimé constitué de plusieurs étages rectangulaires, alimenté par la ligne ground coplanaire (GCPW), adapté dans la bande de fréquence FCC, a servi de base d'étude. Cette antenne a été étudiée dans deux configurations correspondant à deux types d'applications : un format carte de crédit et un format clé USB, principalement distinguées par leur encombrement lié à la largeur des plans de masse. L'étude a débuté avec une structure à plan de masse large et a été suivie, dans une deuxième phase, par des travaux de miniaturisation. La miniaturisation consiste à réduire la largeur des plans de masse en modifiant la géométrie de la structure afin de conserver ses performances radioélectriques. Plusieurs techniques ont été étudiées, notamment la réduction de l'encombrement par repliements 2D et 3D. La technique la plus efficace fut celle basée sur l'insertion de découpes au niveau des plans de masse latéraux ainsi qu'au niveau des plans de masse inférieurs. Une bonne maîtrise des dimensions de ces encoches a permis d'obtenir une structure réduite d'un facteur 5 avec une bonne adaptation sur toute la bande de fréquences. Ces structures ont ensuite été réalisées et les prototypes on tété caractérisés. La caractérisation s'est déroulée lors de plusieurs campagnes de mesures au LEAT et à Orange Labs à La Turbie. Un band de test a été entièrement développé et des mesures dans les domaines temporel et fréquentiel ont permis d'extraire les performances des antennes : gain, diagramme de rayonnement, réponse impulsionnelle, facteur de fidélité, etc... La capacité d'une transmission à travers ces prototypes a été vérifiée en environnement réel. Des débits allant jusqu'à 500Mbits/s ont été atteint. La troisième phase des travaux a consisté à modéliser une puce génératrice d'impulsions ULB et l'intégrer en l'assemblant avec l'antenne dans un système. Cette étude a été réalisée dans la bande de fréquences a dû être conçu. La puce a totalement été modélisée et paramétrée de façon à ce qu'elle soit prise en compte lors de la conception du système. Le projet MIMOC a été achevé avec succès. Le bon partenariat avec tous les membres s'est avéré très constructif et a permis de réaliser le codesign de la partie « antenne » et de la partie « microélectronique ». Suite à ces travaux, un autre projet qui consiste à développer des systèmes communicants en contact avec le corps humain (RUBY) vient de démarrer
Conception d'une antenne bibande à large bande pour la téléphonie mobile by Jean-Marc Carrere( )

1 edition published in 2002 in French and held by 2 WorldCat member libraries worldwide

Antennes quasi-auto-complémentaires pour terminaux mobiles multi-standards by Cédric Requin( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

In this thesis we present the design and optimization of self-complementary antennas to be integrated into a Smartphone. A self-complementary antenna is known as a radio antenna with very interesting bandwidth characteristics. Self-complementarity is based on the Babinet's principle which aims to maximize bandwidth by considering the complementarity of the air and metal in the construction of an antenna. To achieve an objective, the antennas must satisfy a number of criteria, both in terms of performance and also for the design methods and integration. Miniaturization is very sensitive and it is more difficult to implement an antenna because of the physical phenomena limiting performance, especially at low frequency with the new 4G band. In this study we considered initially the self-complementary-IFA on a finite ground plane size: 120x60mm² in order to cover the high frequencies: DCS/PCS/UMTS and WLAN/LTE2600. In the second part, we focused on the possibility of using some improvement techniques by adding structural element (capacitive elements and radiating elements). Various geometrical modifications applied to antenna structures have also been used to obtain results satisfying all criteria, including coverage of LTE800 bands and GSM bands. Several prototypes were used to compare the theoretical results and validate the concept of self-complementarity. We completed the project by developing a way to improve the radio link in natural environments. We have implemented several radiating self-complementary miniature multiband/broadband elements on the same PCB in order to implement the principles of diversity or MIMO
Applications de la ligne microruban suspendue à plan de masse partiel by Georges Kossiavas( Book )

1 edition published in 1981 in French and held by 1 WorldCat member library worldwide

INVESTIGATION BY THE FINITE ELEMENT METHOD OF A SUSPENDED MICROSTRIP LINE WITH PARTIAL MASS PLANE IN ORDER TO OVERCOME THE DISADVANTAGE OF COUPLED MICROSTRIP LINES THAT THEY PROPAGATE EQUAL OR UNEQUAL MODES WITH UNEQUAL PHASE VELOCITIES. APPLICATION OF THESE LINES TO THE SETTING UP OF TRANSIENTS BETWEEN THE VARIOUS CONVENTIONAL STRUCTURES (ESPECIALLY WITH THE COPLANAR LINE) AND DIRECTIONAL COUPLERS WITH NON-UNIFORM LINES
Conception et caractérisation d'antennes imprimées pour systèmes Ultra Large Bande impulsionnels by Nicolas Fortino( Book )

1 edition published in 2006 in French and held by 1 WorldCat member library worldwide

Conception d'antennes miniatures intégrées à leur support pour applications en télémédecine mobile by Hafedh Hamouda( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

This thesis presents the design and the optimization of miniature antennas integrated in specific devices dedicated to ensure communications between medical implants and a mobile phone in the context of telemedicine applications. However, the miniaturization of antennas necessarily implies a degradation of efficiency and bandwidth, which makes it difficult for implementation. Then, the design of electrically small antennas requires a very good understanding of the physical phenomena such as the theoretical limits of performance in terms of bandwidth and efficiency that can be expected for a radiating element with given dimensions. Furthermore, the performance of an electrically small antenna is also highly dependent on the environment in which it is mounted. Therefore, its interaction with each part of its close environment was highlighted and analyzed
Caractérisation et conception d'antennes isotropes miniatures pour objets communicants by Mathieu Huchard( )

1 edition published in 2007 in French and held by 1 WorldCat member library worldwide

Advances made in the fields of wireless sensor networks, radio frequency identification or millimetre-length communications predict the appearance of small, smart and autonomous objects communicating by means of radio frequency transmissions. In this context, the random and variable orientations of the devices with respect to each other cause strong variations of the budget link because of the radiation anisotropy and the polarization mismatches between antennas. Thus, there is a need for low cost small antennas having radiation characteristics optimized for an independent transmission with respect to their relative orientations. The first part of this work consists in proposing a new criterion, called isotropic coverage function, allowing to rigorously characterizing antennas performances in such a context. This method makes it possible to compare various antennas of the literature and to study the effects of their radiation properties. The influence of the propagation environment is also studied. The second part consists in developing two new antennas in response to this issue while taking into account the strong constraints of integration and miniaturization. A prototype is realized and validates the design approach. Finally, a last development considers the case of multi antennas. An extension of the characterization method is proposed. One of the previous structures is enhanced in two versions with two ports and illustrates the principle of a dual polarized isotropic antenna presenting optimized performances
Étude et conception d'antennes miniatures et directives à polarisation circulaire pour lecteurs RFID UHF by Sylvain Pflaum( )

1 edition published in 2013 in French and held by 1 WorldCat member library worldwide

RFID technology is now a part of our daily lives. The corresponding applications are more and more numerous and widespread. This work having been done in the framework of the PACID textile project, this thesis has the ambition to research innovative solutions for RFID readers in order to enhance the management, the traceability and the security of the industrial and commercial textiles.Towards this end, the antenna reader has to be miniature while being low-cost, directive and in circular polarization in the RFID UHF band (0.865-0.868 GHz). The two main technological challenges that we have faced for the reader antenna is managing its main direction of propagation to restrict and control the reading zone as well as the miniaturization of its size in order to easily integrate it into any environment. To respond to this problem, the research areas discussed in this manuscript were: The obtaining of the circular polarization using short-circuited resonators. The study and design of microstrip antennas based on EBG (Electromagnetic Band Gap). Type metamaterials to improve their directivity by using the original properties of these structures. The research of new miniaturization techniques for printed antennas by introducing a new EBG ground plane
Conception de systèmes antennaires MIMO multi-standards LTE pour les nœuds relais by Lamia Sadaoui( )

1 edition published in 2018 in French and held by 1 WorldCat member library worldwide

To deploy the fourth generation called 4G/LTE or "LTE advanced", mobile operators face strong constraints: they must ensure a good geographic coverage but also an excellent quality of service. This requires new methods that go far beyond what has been implemented for GSM or 3G networks. The telecom industry has created the concept of "small cells" that reinforce the "macrocells" deployed by the operators. This thesis tries to provide a solution to this problem and more particularly through the development of antennas for a product called "smart cell". This study, supported by the FUI project NETCOM, should enable mobile operators to extend the coverage and capacity of their networks at a lower cost while maintaining a good quality of service. To do that, the aim of this thesis more particularly is the design of a multi-band multi-antennas MIMO system (Multiple-Input Multiple-Output) dedicated to relay nodes for the deployment of the fourth generation 4G/LTE or "LTE advanced". The antenna design considers the coverage of the three LTE operating frequency bands and must be compatible with them. The (700-900 MHz) frequency band is used for the LTE 700 and LTE 800 bands, (1710-1880 MHz) for the GSM 1800/LTE 1800 bands and the last (2500-2690 MHz) for the LTE 2600 bands. In our first study, a reference system with 4 access was studied in simulation and measured, for only the low band 700-900 MHz. In a second study, we tried to cover the other two higher bands to have a tri-band system using the parasitic elements to get a three-band MIMO system with 4 access. We studied then, the influence of the environment close to the antenna system, with the presence of a metallic radiator. As we often encounter a frequent problem in multi-antenna systems which is the coupling problem between the different access of a multi antenna system, so we have studied and realized a decoupling technique. This technique was used to enhance the isolation between the different access
 
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Alternative Names
Kossiavas, G.

Languages
French (16)

English (1)