In this thesis, we had studied the transmissivity of electromagnetic waves in onedimensional photonic structures composed by metamaterials in many ways. Applying the formalism of transfer matrix, comparing the transmission spectra between two systems: defective photonic superlattices composed of subwavelength slab widths and a simple photonic structures formed by three layers. Through the effective medium theory, with good accuracy, we had shown the equivalence of the above systems in the spectral region in which there are modes of resonant tunneling for both structures. Furthermore, we had derived a general condition which should be satisfied to observe the resonant modes. Our analytical results may be useful from a technological point of view to propitiate, in the design and development of photonic devices, adjustment or selection of resonant frequencies. Finally, we investigated the electromagnetic wave transmission properties through a multilayer system consisting of alternated layers of air and uniaxially anisotropic metamaterials. The optical axis of each heterostructure coincides with the direction of stacking of the layers. The components of the electric permittivity and magnetic permeability tensors that characterize the metamaterial are modeled by a Drude-type response and split-ring resonator metamaterial response, respectively. Different plasmon frequencies are considered for directions perpendicular and parallel to the optical axis. For oblique incidence, longitudinal plasmon polariton modes are found in the neighborhood of the plasmon frequency along the optical axis. The anisotropy leads to unfolding of nearly dispersionless plasmon-polariton bands either above or below the plasmon frequency. Moreover, it is shown that, even in the presence of loss /absorption, these plasmon polariton modes do survive and, therefore, should be experimentally detected. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nessa tese, estudamos a transmissividade de ondas eletromagnéticas em estruturas fotônicas unidimensionais formadas por metamateriais, sob vários aspectos. Aplicando o formalismo de matriz de transferência, comparamos os espectros de transmissão entre dois sistemas: redes defeituosas com camadas no regime de sub-comprimento de onda e simples estruturas fotônicas formadas por três camadas. Através da teoria do meio efetivo, com boa acurácia, mostramos a equivalência dos supracitados sistemas na região espectral em que há modos de tunelamento ressonante para ambas estruturas. Além disso, derivamos uma condição geral que deve ser satisfeita para observarmos os modos ressonantes. Nossos resultados analíticos podem ser úteis do ponto de vista tecnológico por propiciarem, na concepção e no desenvolvimento de dispositivos fotônicos, o ajuste ou seleção das frequências de ressonância. Por fim, investigamos as propriedades de transmissão de ondas eletromagnéticas através de sistemas multicamadas consistindo de camadas alternadas de ar e metamateriais uniaxialmente anisotrópicos. O eixo óptico de cada heteroestrutura coincide com a direção de empilhamento das camadas. As componentes dos tensores de permissividade elétrica e permeabilidade magnética que caracterizam os metamateriais são modeladas por respostas do tipo Drude e split-ring resonator, respectivamente. Diferentes frequências de plasmon são consideradas para as direções perpendiculares e paralela ao eixo óptico. Para incidência oblíqua, modos de plasmon polariton longitudinais são encontrados nas vizinhanças da frequência de plasmon ao longo do eixo óptico. A anisotropia leva ao desdobramento de bandas de plasmon polariton quase sem dispersão acima ou abaixo da frequência de plasmon. Além disso, mostramos que mesmo na presença de perdas/absorções, esses modos de plasmon polariton sobrevivem e, portanto, devem ser detectados experimentalmente.

Ce travail de thèse porte sur l'étude de l'intégration des fonctions d'amortissement vibroacoustique dans des plaques en matériau composite. Dans un premier temps, pour une méta-plaque non composite, les caractéristiques d'atténuation des vibrations ont été étudiées avec un réseau périodique de résonateurs (poutre-masse) attachés à une plaque.L'effet de périodicité et des résonances locales permet de bloquer la propagation d'ondes sur des plages de fréquences données, appelée bandes interdites. Des simulations numériques basées sur la MEF ont permis de calculer les diagrammes de bandes des plaques périodiques et d'analyser la sensibilité de ces bandes interdites aux différents paramètres de conception de méta-plaque. Les calculs de coefficient de transmission d'une onde plane selon la direction perpendiculaire à la zone traitée, mettent en évidence la présence des bandes interdites prédites par le diagramme de bande. Les réponses fréquentielles de plusieurs modèles sont comparées, pour mettre en évidence les écarts entre une structure infinie et une structure finie. Une méthode automatique originale est mise au point pour détecter les gammes de fréquences des bandes interdites pour une méta-plaque finie.Ces méthodes théorique et expérimentale sont alors appliquées à des plaques composites SMC avec des perforations périodiques. Des essais avec une excitation unidirectionnelle et une excitation ponctuelle sont réalisés. L'influence de chaque type de sollicitation sur la réponse vibratoire des plaques est analysée pour mettre en évidence la détectabilité des bandes interdites. Enfin, la robustesse des bandes interdites aux variations du réseau périodique est validée. / The vibration attenuation characteristics of a metamaterial plate were investigated theoretically and experimentally with a 2-dimensional periodic array of resonators (mass-beam) attached to a thin homogeneous plate.The sensitivity analysis of the band gap frequency range took into account the uncertainties of all the design parameters of the metamaterial plate. The theoretical approach used the finite element method (FEM) to compare the predicted band gaps with those derived from infinite and finite models of the metamaterial.An original automatic method is proposed to detect the frequency ranges of band gaps in finite metamaterial based on the behavior of the corresponding bare plate. Directional plane wave excitation and point force excitation were applied to evaluate the efficiency of the detection method. The results of these analyses were compared with experimental measurements. Frequency ranges of experimental vibration attenuation are in good agreement with the theoretically predicted complete and directional band gaps.These theoretical and experimental methods are then applied to SMC (Sheet Molding Compound) composite plates with periodic perforations. Tests with unidirectional excitation and point force excitation are performed. The influence of each type of excitation on the vibratory response of the plates is analyzed in order to demonstrate the detectability of the bands gaps.Finally, the robustness of the band gap to the variations of the periodic lattice is validated following an integration of perturbations: addition of local mass on half of the unit cells according to a periodic or random positions.

Made available in DSpace on 2014-12-17T14:55:54Z (GMT). No. of bitstreams: 1 VitorFB_DISSERT.pdf: 3545980 bytes, checksum: 2759df31b3e705a93ae644db95f0c01f (MD5) Previous issue date: 2012-02-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Microstrip antennas are subject matter in several research fields due to its numerous advantages. The discovery, at 1999, of a new class of materials called metamaterials - usually composed of metallic elements immersed in a dielectric medium, have attracted the attention of the scientific community, due to its electromagnetic properties, especially the ability to use in planar structures, such as microstrip, without interfering with their traditional geometry. The aim of this paper is to analyze the effects of one and bidimensional metamaterial substrates in microstrip antennas, with different configurations of resonance rings, SRR, in the dielectric layer. Fractal geometry is applied to these rings, in seeking to verify a multiband behavior and to reduce the resonance frequency of the antennas. The results are then given by commercial software Ansoft HFSS, used for precise analysis of the electromagnetic behavior of antennas by Finite Element Method (FEM). To reach it, this essay will first perform a literature study on fractal geometry and its generative process. This paper also presents an analysis of microstrip antennas, with emphasis on addressing different types of substrates as part of its electric and magnetic anisotropic behavior. It s performed too an approach on metamaterials and their unique properties / As antenas de microfita s?o objeto de estudo em diversos campos de pesquisa devido a suas in?meras vantagens. A obten??o, em 1999, de uma nova classe de materiais, chamados metamateriais - normalmente compostos por elementos met?licos imersos em um meio diel?trico, tem atra?do a aten??o da comunidade cient?fica, gra?as ?s suas propriedades eletromagn?ticas e, principalmente, pela capacidade de utiliza??o em estruturas planares, tais como a microfita, sem interferir em sua geometria tradicional. O objetivo desse trabalho ? analisar os efeitos do uso de substratos metamateriais uni e bidimensionais em antenas de microfita, com diferentes configura??es de an?is de resson?ncia - SRR - na camada diel?trica. A geometria fractal ? aplicada a esses an?is, na busca de se verificar um comportamento multibanda e de se reduzir a frequ?ncia de resson?ncia das antenas. Os resultados s?o, ent?o, obtidos com o software comercial Ansoft HFSS, usado para a an?lise do comportamento eletromagn?tico das antenas, por meio do M?todo dos Elementos Finitos (FEM). Para tanto, nessa disserta??o, ? previamente realizado um estudo bibliogr?fico sobre a geometria fractal e seu processo gerador. Este trabalho apresenta tamb?m uma an?lise sobre as antenas de microfita, com ?nfase ? abordagem de diferentes tipos de substratos, evidenciando seu comportamento anisotr?pico el?trico e magn?tico. ? realizada, ainda, uma abordagem sobre os metamateriais e suas propriedades singulares

Les surfaces sélectives en fréquence (FSS) pour la furtivité radar ou l’optique ont été largement étudiées. Depuis plus de vingt ans, des matériaux artificiels ont été conçus, permettant d’obtenir des propriétés particulières, notamment l’existence de bandes permises ou interdites, réfraction négative, ultra-réfraction. Par ailleurs, des antennes basées sur la mise en réseau d’un élément rayonnant sont plus compactes et plus facilement intégrables. Le problème de la diffraction d’une onde plane par des réseaux tridimensionnels bipériodiques peut être résolu par éléments finis ou par équations intégrales bipériodiques ; il l’est souvent par une méthode hybride combinant la méthode des éléments finis et la méthode aux équations intégrales. Nous avons choisi de développer une méthode hybride utilisant deux variantes de la méthode aux équations intégrales. Les domaines semi-infinis (l’extérieur du réseau) sont traités par des équations intégrales bipériodiques (EI3D2D), et les domaines bornés (l’intérieur du réseau) sont traités par des équations intégrales tridimensionnelles (EI3D), auxquelles on impose des conditions aux limites de pseudopériodicité. Ce code numérique est développé dans le cadre du code SPECTRE de Dassault-Aviation, qui est un code généraliste 3D, afin de bénéficier de la richesse des modèles qui y ont déjà été développés (modèle composé d’un nombre quelconque de sous-domaines de formes et de matériaux quelconques, traitement des différents cas de jonctions entre sous-domaines, matériaux de faible épaisseur). L’efficacité en termes de précision et en temps de calcul de la méthode numérique est validée par comparaison des résultats avec d’autres simulations numériques et également avec des résultats de mesures. Les cas testés sont représentatifs de plusieurs des principaux phénomènes liés aux métamatériaux : surfaces sélectives en fréquence, transmission « extraordinaire », surfaces à haute impédance. Enfin, nous étudions un radôme passe-bande indépendant à l’angle d’incidence, à l’aide de la méthode numérique que nous proposons. La structure retenue se base sur un réseau de cavités coaxiales dans une couche métallique. Nous expliquons l’origine physique des résonances qui apparaissent et nous suggérons une évolution géométrique du profil des cavités, afin d’augmenter la largeur de bande passante. / Frequency selective surfaces (FSS) for radar stealth or in optics have been widely studied. For more than two decades, articial materials have been designed to highlight specific behaviour, like the existence of allowed or forbidden bands, negative refraction, ultra-refraction... Moreover, antennas based upon an array of radiating elements improve the compactness and integration of these features. The problem of the diffraction of a plane wave by 3D biperiodic scatterers can be solved by finite-elements methods (FEM) or biperiodic boundary integral equations (BIE). It is often done by hybrid methods, that combine FEM and BIE. We choose to develop a hybrid method that uses two variants of the BIE method. Semiinfinite outer domains are treated by biperiodic integral equations (3D2D IE) and inner bounded domains are treated by 3D free-space integral equations (3D IE). Pseudoperiodic boundary conditions are enforced in the scattering biperiodic structure. The numerical code is developed in the framework of Dassault Aviation’s SPECTRE code, which is a general 3D code, in order to take advantage of the various models that have already been developed : arbitrary number of sub-domains of various shapes or materials, treatment of the different types of junctions between sub-domains, thin slabs. The efficiency in terms of accuracy and computation time of the numerical code is validated by comparison of the results from other numerical simulations or measurements. All the test cases are representative of several of the main phenomena that can be observed in metamaterials : FSS, “extraordinary” transmission, high-impedance surfaces. Finally, a bandpass radome which is independent to the angle of incidence is studied. The proposed numerical method is used. The chosen structure is based upon an array of coaxial cavities in a metallic slab. We explain the physical origin of resonances that appear and we suggest a geometrical evolution of the profile of the cavities, to favor a wideband behavior.

Orientador: Hugo Enrique Hernandez Figueroa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-15T19:32:10Z (GMT). No. of bitstreams: 1 Santos_CarlosHenriquedaSilva_D.pdf: 6145760 bytes, checksum: b129064af29e8b7052b13e0b422b299c (MD5) Previous issue date: 2010 / Resumo: Esse trabalho tem por objetivo desenvolver algoritmos bio-inspirados (Algoritmo Genético, Estratégia Evolutiva e Sistema Imunológico Artificial) eficientes (tempo de processamento e convergência), e flexíveis (multi-plataforma), para a otimização de dispositivos eletromagnéticos nos domínios da frequência e do tempo. Além disso, para satisfazer a demanda computacional requerida nessas otimizações, foram implementadas versões paralelas dos algoritmos bio-inspirados e do método das diferenças finitas no domínio tempo em três dimensões (FDTD 3D) para serem executados em cluster de computadores. A eficiência e flexibilidade dos algoritmos desenvolvidos foram confirmadas através da aplicação criteriosa de testes de desempenho disponíveis na literatura. Isto permitiu a proposta e simulação de novos e complexos dispositivos eletromagnéticos baseados em estruturas metamateriais / Abstract: The objectives of this work are to develop efficient (runtime and convergence) and flexible (multiplatform) bio-inspired algorithms (Genetic Algorithm, Evolution Strategy and Artificial Immune System), for the optimization of electromagnetic devices either in frequency and time domain. In addition, to satisfy the computational requirements for these optimizations a parallel version of these bio-inspired algorithms and a three-dimensional finite difference time domain (3D FDTD) were developed capable to be processed in cluster computers. The successful performance of these parallel resources was confirmed by their careful assessment through key tests available in the specialized literature. This permitted the proposal and simulation of novel and complex electromagnetic devices based on metamaterial structures / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

Cette thèse porte sur l’étude numérique et expérimentale de l’utilisation de métamatériaux pour le contrôle des ondes à la surface de l’eau. Dans la première partie, nous avons montré comment focaliser les ondes à la surface de l’eau en utilisant une analogie existant avec des métamatériaux électromagnétiques de permittivité diélectrique quasi nulle qualifiés de ”epsilon-near-zero”. Cela a permis d’adapter le motif de phase à l’interface circulaire entre deux domaines présentant un contraste élevé de profondeur d’eau. L’analogie a donné lieu a un comportement fortement non linéaire des ondes, qui se manifeste par la génération d’une cascade de points focaux associés à des sous-multiples de longueurs d’onde par rapport à l’onde incidente. La deuxième application envisagée des métamatériaux pour les ondes à la surface est de rendre invisible les défauts géométriques d’un guide pour un observateur situé en champ lointain. Dans le premier projet lié au cloaking, des guides d’onde possédant différentes sections transverses ont été analysés. L’efficacité de la bathymétrie, donnée par la cartographie conformationnelle, a été evaluée numériquement en termes de propriétés de diffusion. Dans le second projet, nous avons montré numériquement comment rendre invisible un cylindre qui est décalé de l’axe d’un guide d’onde. Utiliser une bathymétrie de cloaking lisse autour du cylindre permet de reduire de manière significative la dispersion dans une large gamme de frequences. Des experiences réalisées avec des bathymétries conformes aux simulations ont confirmé une augmentation de la transmission par rapport à un scenario de référence avec fond plat. / This thesis presents numerical and experimental results concerning usage of metamaterials for water waves control. Two applications were considered. Firstly, we showed how to focus water waves using analogy to a group of metamaterials called epsilon-near-zero. This allowed to tailor phase pattern at the circular interface between two domains with high contrast in water depth. The analogy resulted in highly nonlinear behaviour of waves, manifested by sub-wavelength cascade of focal spots with respect to the incident wave. The second considered application of metamaterials for water waves was hiding (cloaking) defects in a waveguide from the far-field observer. In the first project, related to cloaking, waveguide with varying cross-sections was analyzed. The efficiency of bathymetry, rendered by conformal mapping, was evaluated in terms of scattering properties. The influence of water waves dispersivity on the cancellation of scattering was also determined. Cloaking properties of the obtained bathymetry were experimentally confirmed using a wave packet characterized by broadband spectrum. In the second project, we showed how to cloak a cylinder that is shifted from the centreline of a waveguide. Smooth cloaking bathymetry surrounding a cylinder was able to significantly reduce the scattering in broad range of frequencies. The experimental counterparts confirmed increase in transmission with respect to a reference case with flat bathymetry. The remainder of the thesis presents novel method for the analysis of fringe profilometry images. Performance of the new method was compared to the Fourier Transform Profilometry. We obtained significant enhancement in spectral capabilities.

Au cours de ces 20 dernières années, une attention particulièrement soutenue a été donnée à l'étude et à la fabrication de matériaux nano-structurés permettant le contrôle de la lumière. Cependant, les propriétés de non-linéarité optique de ces nouveaux matériaux n'ont que très peu été explorées. Partant de ce constat, cette thèse se propose de pourvoir cette insuffisance. L'accent est mis en particulier sur le processus de génération de seconde harmonique à travers deux aspects fondamentaux: (i) le contrôle de l'émission de seconde harmonique pour des matériaux nano-structurés non-linéaires et (ii) l'augmentation de conversion dans des dispositifs photoniques intégrés. Nous présentons un nouveau phénomène de localisation non-linéaire qui a lieu dans des matériaux main-gauche et qui implique un accord de phase isotrope. Nous démontrons analytiquement le processus de localisation dans un milieu homogène main-gauche, avant de mettre en évidence un tel effet dans des cristaux photoniques non-linéaires à l'aide de simulations numériques. L'effet de localisation contra-propagative du second harmonique est utilisé pour le design d'une lentille de second-harmonique. Ce résultat théorique a été démontré numériquement pour une structure réalisable fonctionnant aux fréquences optiques. L'augmentation de génération de seconde harmonique constitue l'aspect complémentaire. En tirant parti de la forte localisation de lumière dans une chaîne de nano-tiges de dimension finie, nous montrons que, pris ensemble, le confinement transverse sub-longueur d'onde et la condition de résonance d'accord de phase contribuent de manière importante à l'augmentation de la génération de seconde harmonique. Les capacités de guidage sub-longueur d'onde de chaînes de nano-tiges sont mis en évidence en examinant leurs propriétés de propagation linéaire. Pour finir, nous nous penchons sur la condition d'accord de phase assurant l'interaction non-linéaire optimale. / The past twenty years have been exceptionally rich on the study and fabrication of nanostructured materials to control light, but no much attention was given to nonlinear optical properties of these novel materials. In this context, the present thesis would partially address this gap. In particular, we focus on the second-harmonic generation process, by considering two fundamental aspects: the second-harmonic emission control by means of nanostructured nonlinear materials and the conversion enhancement in integrated photonic devices. A novel nonlinear localization phenomenon occurring in left-handed materials and involving isotropic phase-matching is presented. We analytically demonstrate the localization process in a homogenous left-handed material and by numerical simulation we show the effect for nonlinear photonic crystals. The backward second-harmonic localization effect is used to design a second-harmonic lens. This interesting theoretical result is numerically shown for a feasible structure working at optical frequencies. The second-harmonic generation enhancement is the complementary aspect. By taking advantage of the strong light localization achieved in finite size dielectric nonlinear nanorod chains, we show that sub-wavelength transversal confinement, together with the resonant phase-matching condition, adds an important property to the second-harmonic generation enhancement. A study of linear propagation properties of nanorod chain structures first evidences its sub-wavelength guiding capabilities. Finally, the phase-matching condition that assures the maximal nonlinear interaction in this kind of structure is presented.

Dans la perspective d’un contrôle ultime de la lumière, les arrivées récentes des cristaux photoniques et des métamatériaux constituent des avancées majeures. Ces matériaux nano-structurés présentant des propriétés optiques inédites nous ouvrent tout un champ de possibilités encore inexploré. En particulier, des milieux d’indice effectif négatif sont rendus concevables. L’objectif de cette thèse est d’étudier d’un point de vue électromagnétique, à l’aide d’outils analytiques et numériques, le comportement de la lumière dans ces structures exotiques. Nous nous penchons sur les boucles de lumières, qui sont des modes localisés d’une structure multi-couches, émergeant du couplage contra-directionnel entre deux guides distincts. Une analyse physique est proposée et un modèle basé sur la théorie des modes couplés est développé. Cela nous permet de décrire avec précision l’excitation d’une boucle de lumière par une source lumineuse, et d’envisager des applications pour la mise en forme de faisceau. Dans une seconde partie, nous étudions des cristaux photoniques unidimensionnels formés par une alternance de milieux d’indices positif et négatif. Lorsque l’indice moyen est nul, une bande interdite aux propriétés nouvelles apparait. Nous montrons que le caractère dispersif des milieux transforme des pics étroits de transmission en larges bandes. Pour caractériser la propagation d’un faisceau dans un tel cristal, nous développons et validons alors un modèle qui nous permet de démontrer le potentiel en matière de mise en forme de faisceau (auto-collimation, focalisation). / In the perspective of an ultimate control of light, the recent arrivals of photonic crystals and metamaterials are major advances. These nano-structured materials with unusual optical properties are opening a whole range of possibilities still unexplored. In particular, negative index media have became conceivable. The aim of this thesis is to study, with an electromagnetic point of view, the behavior of light in these exotic structures, using analytical and numerical tools. We study the light wheels, which are localized modes of a multi-layer structure, emerging from the contra-directional coupling between two separate waveguides. A physical analysis is proposed and a model, based on the coupled mode theory, is developed. This allows us to accurately describe the excitation of a light wheel by a source, and to consider applications for beam shaping. In a second part, we study one-dimensional photonic crystals combining positive and negative index layers whose the average index is equal to zero. A band gap, called zero-n gap, appears and presents new properties that we detail. Index dispersion is shown to broaden the resonant frequencies creating then a conduction band lying inside the zero-n gap. Self-collimation and focusing effects are in addition demonstrated in zero-average index crystals supporting defect modes. This beam shaping is explained in the framework of a beam propagation model by introducing an harmonic average index parameter.

In the thesis presented, three novel uni-planar left handed transmission lines based on Complementary Split Ring Resonators (CSRR) and Complementary Spiral Resonator (CSR) metamaterial particles are proposed for the first time and successfully applied for the performance enhancement of conventional coupled line filters and the design of a full scan leaky wave antenna. Based on the implementation of Complementary Split Ring Resonators (CSRR) a fully planar Composite Right left handed transmission line (CRLH-TL) plus a Dual Composite Right Left Handed transmission line (D-CRLH-TL) are proposed, designed and studied. The CRLH transmission line is realized loading a microstrip host line with CSRR metamaterial particles and capacitive gaps on the conductor strip of the line, while the D-CRLH transmission line is built bridging the capacitive gaps between the CSRR's with inductive connections to induce dual propagation properties in the structure. A further performance enhancement is achieved by a second proposal based on the implementation of Complementary Spiral Resonators (CSRs). The studies applied to the structure reveal that conditions for D-CRLH propagation are created in a transmission line composed only by CSR metamaterial resonant particles as the result of the unique electromagnetic properties acquired by the CSRs etched on the conductor line of a microstrip waveguide. The CSRR/CSR based D-CRLH transmission lines proposed are applied in the design of two enhanced coupled line filters. The implementation is possible for the first time in this work as result of the highly versatile layout features of the left handed transmission lines proposed which among other important geometrical features, allows couplings in both sides of the structure. Enhanced filtering features are reached by the metamaterial based coupled line filters proposed in terms of selectivity and size reduction in comparison with conventional coupled line filters. In the case of the CSRR loaded metamaterial coupled line filter a size reduction of 49% is achieved compared with a filter of similar performance. A further enhancement is reached by the second coupled filter proposed based on CSR metamaterial resonant particles. The CSR coupled filter proposed reach a roll off rate improvement of 8 dB/GHz and size reduction of 43% in comparison with a conventional coupled line filter of the same order. When this is compared against a conventional coupled line filter of similar performance but higher order, a remarkable size reduction of 77% is achieved by the proposed CSR coupled line filter. Finally, the CSR loaded D-CRLH transmission line is applied in the design of a fully planar leaky wave antenna. Using the CSR structures etched on the conductor line of a microstrip as part of the radiation mechanism altogether with the D-CRLH propagation features of the structure. A full scan radiation pattern is created with backward, forward and broadside radiation as result of the left handed propagation band, right handed propagation band and the balanced transition between them. Two leaky wave antennas are designed to operate at the centre frequencies of 12.5GHz and 6.0GHz. In order to corroborate the performance the CSR D-CRLH leaky wave antenna operating at 6.0GHz is fabricated and measured showing a scanning range of 30 deg with a maximum gain of 13.2 dBi.

La communauté des métamatériaux est entrée en effervescence depuis la publication de deux articles de Science en 2006 par Pendry et Leonhardt dans lesquels il est proposé de réaliser des systèmes exotiques tels que les capes d’invisibilité par transformation d’espace. En effet, l’invariance de forme des équations de Maxwell permet une équivalence entre géométrie déformée et présence d’un matériau aux propriétés particulières. Depuis, de nombreux exemples expérimentaux ont montré la faisabilité de tels systèmes transformés. L’invariance de forme se retrouve également dans d’autres phénomènes physiques et les transformations d’espace ont par ailleurs été appliquées à plusieurs disciplines telles que l’acoustique, l’élasto-dynamique ou la propagation d’ondes de surface. Nous présentons ici les transformations d’espace appliquées à l’équation de la chaleur. Au cours de notre étude, nous nous intéressons aux transformations menant aux capes d’invisibilité thermiques et aux concentrateurs thermiques. Ces systèmes sont constitués de matériaux anisotropes et hétérogènes ce qui les rend difficile à réaliser. Nous utilisons donc la théorie de l’homogénéisation à deux échelles qui permet d’approcher le comportement de ces systèmes par une alternance de couches de matériaux isotropes. Nous suivons une démarche systématique d’évaluation quantitative des performances de nos systèmes approchés dans une optique d’une ingénierie à haut niveau de métamatériaux thermiques. Un modèle de tapis thermique à 50 couches est proposé dont les résultats expérimentaux sont attendus. / The metamaterials community has been heavily excited since the publication of two articles by Pendry and Leonhardt in 2006 in which exotic devices such as invisibility cloaks are proposed to be implemented by space transformation. Indeed, the form invariance of the Maxwell equations allow for an equivalence between a deformed geometry and a material with specific properties. Since then, several experimental studies have shown the feasibility of such transformed devices. The form invariance is also found in other physical domains such and the space transformations were applied to mulitphyscial phenomena such acoustic wave propagation, elasto-dynamic wave and surface wave propagation. We present in this work the space transformation applied to the heat equation. Throughout our study, we focus on the transformations leading to thermal invisibility cloaks and thermal concentrators. Those transformed devices are made of anisotropic heterogeneous materials which make them difficult to practically design. Therefore, we make use of the two-scale homogenization theory allowing to approach the behavior of those devices with an alternate set of isotropic materials. We systematically try to evaluate quantitatively the performance of our approximate devices by defining an effectiveness criterion to achieve high level of mthermal metamaterials engineering. We present a the end a model of a 50-layer carpet cloak whose first results are to be expected.