A wide-angle incidence, broadband rectified metasurface for radar frequency band EM energy harvesting and wireless power transfer

Abstract

Traditional power transmission networks with complex physical wiring have struggled to meet the power needs of emerging portable and decentralized devices. Recently, rectified metasurfaces for electromagnetic (EM) energy harvesting have attracted great attention from researchers due to their customizability and application flexibility. However, many previous structures mainly focused on harvesting efficiency and ignored harvesting bandwidth. Here, we propose a broadband rectified metasurface structure for radar frequency band EM energy harvesting and wireless power transfer. The cell structure consists of a centrosymmetric hyperbolic ring (CHR) structure that can exhibit an EM wave absorptivity of greater than 80 % at wide incidence angles. The AC energy of each cell is exported through metal vias, and the energy is pooled through the feed networks. Finally, the rectification circuit is designed to complete the AC-to-DC conversion and the DC energy harvesting. Broadband EM energy harvester can be achieved when the incidence angle is 0° to 60°. The half-power bandwidth (HPBW) can be up to 55 % with a normal incidence. To verify the rectified metasurface function, a prototype with 6 × 6 metasurface array is fabricated and tested. When the rectified metasurface operates at 6.1 GHz, RF-to-DC energy harvesting efficiency of greater than 35 % can be achieved in the incidence angle range of 0° to 60° and maximum efficiency is 57 %. It makes it possible to self-power sensor network nodes working in the vicinity of communication base stations or radar base stations.