Abstract

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.

Highlights

  • Several works have improved the performance of metasurface EM energy harvesters which include increasing the harvesting bandwidth by introducing an array of bow-tie CSRRs22 and enhancing the harvesting efficiency up to near unity using an ensemble of electric-inductive-capacitive (ELC) resonators[23]

  • The designed metasurface harvester provides a harvesting efficiency of more than 90% in both frequency bands of interest for any polarization angle of the incident wave which is validated by performing laboratory measurements

  • We presented the design of a novel metasurface for dual-band and multi-polarization electromagnetic energy harvesting

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Summary

Electromagnetic Energy Harvesting

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. A harvesting efficiency of 90%, 83% and 81% at the frequency bands of 0.9 GHz, 2.6 GHz and 5.7 GHz, respectively, was reported To achieve such a high efficiency, the load resistance was required to be very high (around 3 kΩ) which differs considerably from the input impedances of microwave power combining networks, restricting the application in a real-world harvesting system. In two parallel works, multi-polarization EM energy harvesting in the frequency band of 2.4 GHz was achieved using arrays of ELC resonators[21,26] In these designs, each unit cell is connected to one and two terminals with input impedance of 150 Ω and 200 Ω21,26.

Terminating criteria met?
Two pixels adjoin only at a corner vias connected edge capacitors
Transmitter Antenna
Experimental Verification
Conclusion
Author Contributions
Findings
Additional Information
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