The possibility to tailor an electromagnetic (EM) wave is essential for a wide variety of practical applications at both optical and microwave (MW) frequencies. At MWs, the most common approach is based on phased arrays, whose radiation pattern can be tailored by acting on the excitations of the constituting antenna elements. On the contrary, in optics, the manipulation of a light beam was typically performed by exploiting the propagation path inside bulky components. With the advent of metasurfaces (MTS), i.e., arrays of electrically small particles, a new paradigm for structuring at will an arbitrary EM beam has emerged. Indeed, the phase and amplitude response of a MTS can be locally controlled to mold the overall reflected/transmitted field in almost an arbitrary way.
Although MTSs are expected to play a fundamental role in many branches of physics and industrial applications (e.g. 5G and beyond communications, biomedical theranostics, IoT, autonomous driving, and smart environments), they still suffer of several important that prevent their spread in practical scenarios. First of all, the MTS design is typically performed by limitations practical scenarios considering ideal excitation conditions, which are quite far from the ones that may be found in realistic scenarios. On the other hand, when more realistic conditions are considered, the design is mainly based on complex and time-consuming numerical optimization strategies, which can be applied only to simple and idealized scenarios and often lead to non-optimal designs. These issues are even more critical when the response of the MTSs should be controlled in real-time for adapting their behavior to fast-changing operative environments, as explicitly requested by the standard of modern wireless systems.
The overall objective of this project is to investigate innovative solutions to overcome most of the limitations affecting MW MTSs and to apply them for designing application-ready MW components. The fundamental idea is to develop more accurate and effective tools for the MTS physical modelling and design, which allows implementing MTS-based devices with novel functionalities and enhanced performance. In particular, the EM modelling of MTs will be enriched by taking into account some physical phenomena (i.e., spatial dispersion, impedance mismatch due to non-locality, multipolar response of the meta-atoms, etc.) that have been neglected so far but play a crucial role in most of the applicative scenarios. In parallel, the project aims to build a radically-new design paradigm based on inverse scattering and able to fully account for the complex excitation conditions of realistic scenarios.
The combination of these two approaches will also allow to define more practical and effective strategies to reconfigure the MTSs behavior according to changing operative conditions.
The outcomes of the project will be measured through the implementation of some application-ready MTS-based devices at MW frequencies.