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International audience; L’étude s’intéresse à la caractérisation électromagné-tique par une méthode en cavité résonante de composites sol-gel dopés en ferrofluide de maghémite. Nous avons déposé ces sol-gels par trempage/retrait sur un substrat d’alumine pour les mesurer en cavité pour extraire la permittivité et la perméabilité de ces derniers. Les résul-tats de mesures présentées dans ce papier sont pour deux épaisseurs différentes de sol-gel déposée sur le substrat.

Current and future wireless communications systems have to be smart while proposing an acceptable quality of service for given applications and optimized resource management in terms of energy consumption and spectral occupation. Moreover, the demand for nomadic devices is growing, thus requiring light, low profile and miniaturized microwave components which can easily integrate into complex systems. All these requirements can be contradictory for the conventional microwave engineer since for instance, miniaturization is usually achieved with a non-negligible impact on overall performances. Since metamaterials can be tailored to present required electromagnetic properties, it should definitely provide for a higher degree of freedom in the design of both radiative and non-radiative components for wireless systems. The potential of metamaterial to improve the performances of microwave devices should also be considered. This chapter is divided in two main parts: the first one deals with metamaterial applications for non-radiative microwave components and the second one describes the potential and applications of metamaterials to microwave antennas.

International audience

International audience

Time-varying wave propagation and time-harmonic wave propagation in biisotropic materials are reviewed and the connection between the formulations is established via the temporal Fourier transform. An alternative method to determine the dispersive properties of a bi-isotropic slab from sinusoidal scattering data at normal incidence is presented. A numerical example (realistic, synthetic scattering data) is given to illustrate the theory. Furthermore, experimental data is presented and used to generate the permittivity, permeability, and chirality parameters of a specific man-made chiral slab in the range 3.5–18 GHz. On the basis of the results of inversion, the question whether the passivity concept is too austere is raised.

We present our work on metamaterials at the Vrije Universiteit Brussel, Brussels, Belgium. In the first part, we review our work on nonlinear Fabry-Perot based resonators with left-handed materials in the cavity. We show that a material with negative index of refraction can be used for the engineering of the overall diffraction strength inside the cavity. Negative diffraction can be applied for the stabilisation of Fabry-Perot based devices, whereas nearly zero diffraction allows for light patterns (periodic dissipative structures and localized cavity solitons) beyond the normal diffraction limit. In the second part, we discuss planar optical waveguides with metamaterials. We show that a left-handed material cloak in the cladding layer can be used to achieve confinement of light in waveguides with sub-wavelength thickness.