Étude théorique et expérimentale de la propagation des ondes hyperfréquence TM dans une structure périodique PDF Download

Author: Pierrette Fardeau
Publisher:
ISBN:
Category :
Languages : fr
Pages : 74

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Author: Philippe Mariage
Publisher:
ISBN:
Category :
Languages : fr
Pages : 241

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De nombreuses applications des radiocommunications utilisant une porteuse hyperfréquence font intervenir des phénomènes de propagation par chemins multiples. La planification des systèmes de télécommunication envisagés dans ce travail nécessite la réalisation d'outils de prédiction. Ceux-ci ont été élaborés en utilisant une méthode numérique haute fréquence: la Théorie Uniforme de la Diffraction (TUD). Dans cette théorie, le concept de rayon de l'Optique Géométrique est étendu aux phénomènes de diffraction, ce qui permet de prendre en compte les trajets multiples suivis par l'onde rayonnée. Après avoir étudié au préalable et de manière approfondie la configuration canonique du dièdre électrique faiblement conducteur à bord droit, nous avons effectué des comparaisons théoriques et numériques entre les méthodes de prédictions approchées classiques des pertes en milieu urbain et des modèles basés sur la T.U.D. Nous avons également modélisé le cas d'une bifurcation entre deux couloirs de bâtiment, le but étant de définir le couplage moyen obtenu au passage de ce type de transition. Dans le cadre de la propagation en tunnel, nous avons envisagé le cas important de la présence d'une rame située entre l'émetteur et le récepteur. La perturbation apportée par le masquage de cette rame sur le niveau moyen du champ est analysée en considérant le cas d'un rétrécissement localisé de la section droite du tunnel

Author: Rudolf Kompfner
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 56

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Author: Sir John Townsend
Publisher:
ISBN:
Category : Electric conductivity
Languages : en
Pages : 112

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Author: George I. Haddad
Publisher: Modern Frontiers in Applied Sc
ISBN:
Category : Science
Languages : en
Pages : 608

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Author: Agnes Buka
Publisher: World Scientific
ISBN: 1848167997
Category : Science
Languages : en
Pages : 299

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The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.

Author:
Publisher:
ISBN:
Category : Television
Languages : en
Pages : 18

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Report to the President on investigation no. 332-95 under section 332 of the Tariff Act of 1930, as amended.

Author: Stefano Boccaletti
Publisher: A I P Press
ISBN:
Category : Mathematics
Languages : en
Pages : 384

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The 8th Experimental Chaos Conference again demonstrated the broad spectrum of areas where nonlinear dynamics plays an important role, such as circuits, hydrodynamics, optics, chemistry, fracture dynamics, neuroscience, and cognitive science. Additional contributions outline the trends for development and application of concepts and techniques of nonlinear dynamics.

Author: Jerome V. Moloney
Publisher: Springer Science & Business Media
ISBN: 9780387985817
Category : Business & Economics
Languages : en
Pages : 270

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Book Description
Mathematical methods play a significant role in the rapidly growing field of nonlinear optical materials. This volume discusses a number of successful or promising contributions. The overall theme of this volume is twofold: (1) the challenges faced in computing and optimizing nonlinear optical material properties; and (2) the exploitation of these properties in important areas of application. These include the design of optical amplifiers and lasers, as well as novel optical switches. Research topics in this volume include how to exploit the magnetooptic effect, how to work with the nonlinear optical response of materials, how to predict laser-induced breakdown in efficient optical devices, and how to handle electron cloud distortion in femtosecond processes.

Author: Helen Gavaghan
Publisher: Springer Science & Business Media
ISBN: 1461216184
Category : Technology & Engineering
Languages : en
Pages : 311

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In this, the first history of artificial satellites and their uses, Helen Gavaghan shows how the idea of putting an object in orbit around the earth changed from science fiction to indispensable technology in the twinkling of an eye. Focusing on three major areas of development - navigational satellites, communications, and weather observation and forecasting - Gavaghan tells the remarkable inside story of how obscure men and women, often laboring under strict secrecy, made satellite technology possible. "...a gripping read." -NEW SCIENTIST