A dual-band and polarization-independent electromagnetic energy harvester composed of an array of pixelated unit cells is proposed. The pixelated unit cell is basically a dual-band resonator loaded with two resistors which model the input impedance of a power combining circuit in a complete harvesting system. To design the unit cell, a topology optimization approach based on pixelization of the surface of the unit cell and application of a binary optimization algorithm is used. The optimization goal is set to maximize harvesting efficiency at 2.45 GHz and 6 GHz. In our design, full symmetry of the unit cell is considered to achieve insensitivity to the polarization of the incident wave. Once, the unit cell is designed, as a proof of the concept, a metasurface harvester composed of 9 × 9 pixelated cells is designed. The full-wave electromagnetic simulation results demonstrate that the proposed metasurface absorbs the incident electromagnetic wave energy with nearly unity efficiency at both frequencies of interest and irrespective the polarization of the incident field while simultaneously delivering the absorbed power to the loads. To validate the simulations, the metasurface harvester is fabricated and tested in an anechoic chamber. A strong agreement between the simulation results and measurements is observed.
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 9 × 9 resonator array working at 2.45 GHz 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.
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