Conception et implémentation de nouvelles configurations de matrice de Butler en technologies planaire et conforme

Dans ce rapport, nous présentons des nouvelles configurations de matrice de Butler en technologies planaire et conforme. L'étude comporte deux volets portant respectivement sur la conception d'une matrice de Butler à large bande ayant 3 GHz de bande passante (opérant de 4.5 jusqu'à 7.5 GHz), et la conception d'une matrice de Butler conforme à 2.4 GHz. Dans un premier temps, nous présentons une étude théorique et expérimentale de deux coupleurs qui sont les composants clés de la matrice de Butler large bande. Le premier coupleur est directionnel, large bande, à couplage par fente et conçu en technologie CB-CPW, permettant d'éviter l'utilisation de croissements dans la matrice de Butler grâce à sa caractéristique multicouches. Le deuxième coupleur, étant directionnel et large bande, conçu en topologie elliptique et en technologie CBCPW, permettant ainsi de minimiser les pertes et d'assurer une bande passante plus large comparé aux coupleurs hybrides conventionnels. La matrice de Butler, ainsi conçue à base de ces deux coupleurs, offre des bonnes performances couvrant la bande de 4.5 jusqu'à 7,5 GHz. Dans l'étape suivante, nous détaillons nos travaux de recherches liés à une architecture de matrice de Butler conforme opérant à 2.4 GHz en technologie microruban. La topologie conforme à été déjà explorée avec les réseaux d'antennes de différentes formes (cylindriques, sphériques...). L'originalité de nos travaux de recherche, consiste à mettre au point tout un système d'antenne intelligente (matrice de Butler + réseau d'antennes) en topologie conforme permettant de lever le défi concernant la géométrie, ce qui facilite l'intégration du système à n'importe quel milieu de travail et évite les coûts d' installations supplémentaires. En plus avoir le système d'antenne intelligente en entier conforme (réseau d'antenne + matrice de Butler), permet d'avoir une couverture de 360° dépendamment de sa configuration. Les résultats obtenus ont montré des bonnes performances en termes de directivité et de contrôle de diagramme de rayonnement. Une étude paramétrique concernant l'effet de la courbure de la structure sur les diagramme de rayonnement a été détaillée dans la suite

Multistatic radar optimization for radar sensor network applications

The design of radar sensor networks (RSN) has undergone great advancements in recent years. In fact, this kind of system is characterized by a high degree of design flexibility due to the multiplicity of radar nodes and data fusion approaches. This thesis focuses on the development and analysis of RSN architectures to optimize target detection and positioning performances. A special focus is placed upon distributed (statistical) multiple-input multipleoutput (MIMO) RSN systems, where spatial diversity could be leveraged to enhance radar target detection capabilities. In the first part of this thesis, the spatial diversity is leveraged in conjunction with cognitive waveform selection and design techniques to quickly adapt to target scene variations in real time. In the second part, we investigate the impact of RSN geometry, particularly the placement of multistatic radar receivers, on target positioning accuracy. We develop a framework based on cognitive waveform selection in conjunction with adaptive receiver placement strategy to cope with time-varying target scattering characteristics and clutter distribution parameters in the dynamic radar scene. The proposed approach yields better target detection performance and positioning accuracy as compared with conventional methods based on static transmission or stationary multistatic radar topology. The third part of this thesis examines joint radar and communication systems coexistence and operation via two possible architectures. In the first one, several communication nodes in a network operate separately in frequency. Each node leverages the multi-look diversity of the distributed system by activating radar processing on multiple received bistatic streams at each node level in addition to the pre-existing monostatic processing. This architecture is based on the fact that the communication signal, such as the Orthogonal Frequency Division Multiplexing (OFDM) waveform, could be well-suited for radar tasks if the proper waveform parameters are chosen so as to simultaneously perform communication and radar tasks. The advantage of using a joint waveform for both applications is a permanent availability of radar and communication functions via a better use of the occupied spectrum inside the same joint hardware platform. We then examine the second main architecture, which is more complex and deals with separate radar and communication entities with a partial or total spectrum sharing constraint. We investigate the optimum placement of radar receivers for better target positioning accuracy while reducing the radar measurement errors by minimizing the interference caused by simultaneous operation of the communication system. Better performance in terms of communication interference handling and suppression at the radar level, were obtained with the proposed placement approach of radar receivers compared to the geometric dilution of precision (GDOP)-only minimization metric

Differentiation of Fanconi anemia and aplastic anemia using mitomycin C test in Tunisia

International audienceFanconi anemia (FA) is a recessive chromosomal instability syndrome that is clinically characterized by multiple symptoms. Chromosome breakage hypersensitivity to alkylating agents is the gold standard test for FA diagnosis. In this study, we provide a detailed laboratory protocol for accurate assessment of FA diagnosis based on mitomycin C (MMC) test. Induced chromosomal breakage study was successful in 171 out of 205 aplastic anemia (AA) patients. According to the sensitivity of MMC at 50 ng/ml, 38 patients (22.22%) were diagnosed as affected and 132 patients (77.17%) as unaffected. Somatic mosaicism was suspected in an 11-year-old patient with a FA phenotype. Twenty-six siblings of FA patients were also evaluated and five of them (19.23%) were diagnosed as FA. From this study, a standard protocol for diagnosis of FA was developed. It is routinely used as a diagnostic test of FA in Tunisia