Design of Simple Dual-Band RF Energy Harvester Using CSRR Metasurface for Low-Power Devices

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This article presents a simple, low-cost, dual-band RF energy harvester, which includes a metasurface array and a low-cost rectifier. The metasurface unit consists of a solid patch with two through vias, in which squared complementary split ring resonators (CSRRs) are etched. By combining CSRR with different sizes, two current distributions are created, thereby achieving dual-band characteristic. Then, microstrip lines are introduced into the unit to release the energy constrained within the resonators, further enhancing current aggregation at through vias and improving energy harvesting efficiency. The low-cost rectifier adopts a single-series topology, ensuring RF-dc conversion at a low input power level of −10 dBm. To validate the design, a <tex-math notation="LaTeX">5× 5</tex-math> metasurface prototype together with a single-series rectifier has been fabricated and measured. The measured results show that the maximum harvesting efficiency of the proposed metasurface is 90.4% at 2.05GHz and 86.5% at 3.05GHz. At a large incidence angle of 60°, the maximum efficiency in the operating bands (2–2.1 and 3–3.1 GHz) reaches 68.3% and 76.6% under TE polarization and 78.4% and 65.2% under TM polarization, with the lower operating frequency unchanged. For the proposed energy harvester, the optimal RF-dc efficiency reaches 20.9% at an incident power density of <tex-math notation="LaTeX">17.7~μ</tex-math> W/cm2 and normal incidence. The proposed harvester exhibits dual band, high harvesting efficiency, and simple structure, making it suitable for providing sufficient energy to low-power electronic devices and wireless sensor networks in complex environments.