Dynamic Metasurfaces for Energy Concentration

In this talk, we put forward the concept of metasurface energy concentrator which can fully reflect waves incident from multiple directions into one direction. The proposed structure is based on a spatiotemporally modulated impedance sheet mounted on a grounded substrate. We show what proper traveling-wave modulations of the sheet impedance provide this functionality. We introduce a general analysis and design method based on the generalized transmission-line model. Using mathematical optimizations, we demonstrate three-port and four-port designs of energy concentrators.