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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design Of A Wideband Dual-polarized Cavity Backed Slot Antenna

Paryani, Rajesh 01 January 2010 (has links)
A new technique for designing wideband dual-polarized cavity-backed slot antennas is presented. The structure is in the form of a double-resonant, dual-polarized slot antenna backed by a shallow substrate integrated cavity with a depth of approximately one tenth the free space wavelength. The presence of the cavity behind the slot enhances the antenna's directivity and reduces the possibility of surface wave propagation in the antenna substrate when the element is used in an array environment. Moreover, the dual-polarized nature of this radiating element may be exploited to synthesize any desired polarization (vertical, horizontal, RHCP, or LHCP). The double-resonant behavior observed in this substrate-integrated cavity-backed slot antenna (SICBSA) is utilized to enhance its bandwidth compared to a typical cavity-backed slot antenna. A prototype of the proposed antenna is fabricated and tested. Measurement results indicate that a bandwidth of 19%, an average gain of 5.3 dB, and a wideband differential isolation of 30 dB can be achieved using this technique. The principles of operation along with the measurement results of the fabricated prototype are presented and discussed in this dissertation. The SICBSA is investigated as a candidate for use as an array element. A uniform two element phased array is demonstrated to locate the main beam from boresight to thirty degrees. The potential effects of mutual coupling and surface wave propagation are considered and analyzed.
2

Conception de systèmes d'alimentation sans contact pour la traction ferroviaire / Design of contactless supply system for railway traction.

Sibué, Jean-Romain 13 December 2011 (has links)
Les travaux présentés dans cette thèse portent sur la conception et le dimensionnement de composant magnétique dédié au transfert d'énergie sans contact pour des applications ferroviaires de type tramway. Cette famille de composant présente un comportement fortement inductif. Un convertisseur à double fréquence de résonance est utilisé pour l'alimenter et compenser l'énergie réactive du coupleur. Pour parvenir à dimensionner ce composant et son convertisseur associé, un outil d'aide au dimensionnement a été mis au point. Celui-ci est basé sur des modèles analytiques du composant magnétique et de la structure d'électronique de puissance. Une fois le dimensionnement réalisé, une étude des pertes, dans les bobinages et les circuits magnétiques, est réalisée par simulation numérique en utilisant la méthode d'homogénéisation (représentation macroscopique des éléments avec des propriétés électromagnétiques complexes). Puis, la modélisation du comportement thermique du système est présentée afin de garantir la température de fonctionnement désirée. Afin de valider l'approche de dimensionnement et les outils mis en place, des expérimentations ont été menées sur des prototypes de 1,6 et 100 kW. Les résultats obtenus ont montré la précision et la pertinence de l'approche théorique. Cette étude valide la faisabilité de ce type de système forte puissance. / The works presented in this thesis deal with the design and the sizing of magnetic component dedicated to contactless energy transfer for railway application like tramway. This family of component presents a strongly inductive behavior. A double resonance converter is used to supply and compensate reactive energy of transformer. In order to design this component and its associated converter, a design tool has been implemented. This one is based on analytical models of magnetic component and power electronic converter. One time designing realized, a study of losses, in windings and in magnetic cores, is realized by numerical simulation by using homogenization method (macroscopic representation of elements with electromagnetic complex properties). Then, the establishment of a model of thermal behavior of system is presented in order to guarantee desired working temperature. In order to check designing approach and tools, experimentations have been performed on prototypes of 1.6 and 100 kW. Obtained results show the accuracy and relevance of theoretical approach. Moreover, this study confirms the feasibility of this kind of high power system.

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