Analysis and design of metasurface antennas based on temporal metastructures

In this contribution, we present the analysis and design of a novel class of metasurface-based antennas, whose radiative capabilities are enabled by temporal (time-switched) metamaterials. In particular, we consider a thin metasurface supporting the propagation of a surface wave that can switch instantaneously from a finite capacitive value of the surface impedance to an open circuit, resulting in a temporal interface. We demonstrate that after the temporal switch of the metasurface properties, the surface wave is instantaneously coupled to free space realizing a highly directive beam in end-fire direction. Thanks to wavenumber conservation across a temporal interface, we demonstrate that the proposed metasurface-based antenna can radiate at a much higher frequency with respect to the source frequency. Analytical formulations and numerical simulations are provided to predict and verify the frequency upshift and the radiation characteristics of the proposed novel antenna.