The performance of conventional antenna architectures is limited by inherent trade-offs among bandwidth, efficiency, scan range and size. Disruptive concepts are necessary to address the demanding requirements arising in novel applications such as satellite and 5G communications, and high-resolution imaging.
Metasurfaces (MSs) are electrically thin arrays of subwavelength scatterers and have recently emerged as a promising concept to attain unprecedented antenna performance and functionalities. The subwavelength periodicity of a MS offers an extremely fine control on the aperture fields and, by virtue of Huygens’ principle, the possibility to perform a wide range of transformations of the incident field.
This thesis, available at the CEA-Leti, Laboratory of Antennas, Propagation and Inductive Coupling, aims to provide a mathematical framework for the analysis and design of metasurfaces lenses and to demonstrate groundbreaking ultralow-profile antenna systems comprising a primary source and a metalens realized with a few cascaded layers. The metalens will be modeled as an effective bianisotropic medium, exhibiting coupled responses to electric and magnetic fields. Specific synthesis procedures will be developed to engineer the frequency dispersion of a large metalens and to tailor its refractive index as a function of the incident angle of the impinging wave.