Time‐Varying Metasurfaces for Efficient Surface‐Wave Coupling to Radiation and Frequency Conversion

Time‐varying electromagnetic materials are introducing new ways to control and transform light waves, unlocking unexplored scattering phenomena. In this paper, the wave phenomena associated with abrupt changes in the surface impedance of a metasurface introduced uniformly in space, forming a time interface are investigated. Efficient transformation of a monochromatic surface wave propagating along the metasurface into a radiated wave at a significantly higher frequency is demonstrated. This phenomenon realizes an efficient radiator for electromagnetic wireless signals at high frequencies relying on generators and modulators operated at a much lower frequency.