Multi-polarisation electromagnetic energy harvesting with high efficiency

This study presents a polarisation-independent metasurface harvester composed of an ensemble of novel electric-field-coupled inductive-capacitive (ELC) resonators. The ELC resonator has full symmetry in a way that its behaviour is highly insensitive to the polarisation of the incident wave. Loading the resonators with resistors (which model the input impedance of a power combining circuit in a harvesting system), it is shown that the metasurface absorbs the incident electromagnetic wave energy, with nearly unity harvesting efficiency, irrespective of its polarisation while simultaneously delivering the absorbed power to the loads. As a proof of concept, a metasurface harvester composed of a 9x9 resonator array working at 2.45GHz was fabricated. Near-unity harvesting efficiency of the metasurface was demonstrated using full-wave numerical simulation for a wide range of polarisation angles. Laboratory tests showed strong agreement between the simulation results and the measurements.