Direct dark mode excitation by symmetry matching of a single-particle based metasurface

This paper makes evidence for direct dark mode excitation mechanism in a metasurface structure. The dark mode excitation mechanism is entirely determined by structures' symmetry and does not depend on near-field coupling between elements. In our examples, we consider single element based metasurface composed of two V antennas connected in an anti-symmetric arrangement. Both experimental and modeling results show an efficient excitation of magnetic dipolar mode in such structures. The direct dark mode excitation mechanism provides a design that is more robust with respect to technology imperfections. The considered approach opens promising perspectives for new type of nanostructure designs and greatly relaxes fabrication constraints for the optical domain.Comment: 21 pages, 5 figure

Ultra directive antenna via transformation optics

Spatial coordinate transformation is used as a reliable tool to control electromagnetic fields. In this paper, we derive the permeability and permittivity tensors of a metamaterial able to transform an isotropically radiating source into a compact ultradirective antenna in the microwave domain. We show that the directivity of this antenna is competitive with regard to conventional directive antennas horn and reflector antennas, besides its dimensions are smaller. Numerical simulations using finite element method are performed to illustrate these properties. A reduction in the electromagnetic material parameters is also proposed for an easy fabrication of this antenna from existing materials. Following that, the design of the proposed antenna using a layered metamaterial is presented. The different layers are all composed of homogeneous and uniaxial anisotropic metamaterials, which can be obtained from simple metal-dielectric structures. When the radiating source is embedded in the layered metamaterial, a highly directive beam is radiated from the antenn

Antenna Design Concepts Based on Transformation Electromagnetics Approach

Using the idea of wave manipulation via coordinate transformation, we demonstrate the design of novel antenna concepts. The manipulation is enabled by composite metamaterials that realize the space coordinate transformation. We present the design, realization and characterization of three types of antennas: a directive, a steered beam and a quasi-isotropic one. Numerical simulations together with experimental measurements are performed in order to validate the concept. Near-field cartography and far-field pattern measurements performed on a fabricated prototype agree qualitatively with Finite Element Method (FEM) simulations. It is shown that a particular radiation can be transformed at ease into a desired one by modifying the electromagnetic properties of the space around it. This idea can find various applications in novel antenna design techniques for aeronautical, telecommunication and transport domains

Structures périodiques et métamatériaux. Antennes et dispositifs électromagnétiques.

Ce manuscrit présente une synthèse de mes travaux de recherche effectués depuis l’obtention de mon doctorat en Novembre 2005. Il détaille les différents cadres de ces travaux, notamment si les projets ont été effectués en collaboration avec d’autres groupes de recherche universitaires ou industriels et si les projets se déroulaient sur le plan national ou international. S’y trouve aussi une liste détaillée des différents encadrements auxquels j’ai contribué, ainsi qu’une liste de mes publications en relations avec mes travaux de recherche. Les publications majeures de cette liste sont regroupées dans un document annexe.Mes travaux de recherche, qui sont effectués dans le domaine des microondes, sont regroupés sous deux thèmes bien distincts :1. Métasurfaces et antennes,2. Structures à gradient, antennes et dispositifs microondes

Waveguide taper engineering using coordinate transformation technology

Spatial coordinate transformation is a suitable tool for the design of complex electromagnetic structures. In this paper, we define three spatial coordinate transformations which show the possibility of designing a taper between two different waveguides. A parametric study is presented for the three transformations and we propose achievable values of permittivity and permeability that can be obtained with existing metamaterials. The performances of such defined structures are demonstrated by finite element numerical simulations

Customised broadband metamaterial absorbers for arbitrary polarisation

This paper shows that customised broadband absorption of electromagnetic waves having arbitrary polarisation is possible by use of lossy cut-wire (CW) metamaterials. These useful features are confirmed by numerical simulations in which different lengths of CW pairs are combined as one periodic metamaterial unit and placed near to a perfect electric conductor (PEC). So far metamaterial absorbers have exhibited some interesting features, which are not available from conventional absorbers, e.g. straightforward adjustment of electromagnetic properties and size reduction. The paper shows how with proper design a broad range of absorber characteristics may be obtained.Comment: 12 pages, 5 figures, submitted to Optics Expres

High-Q Fano resonances via direct excitation of an antisymmetric dark mode

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