Electrically small particles combining even- and odd-mode currents for microwave energy harvesting

We present a structure composed of an ensemble of electrically small resonators for harvesting microwave energy. A flower-like structure composed of four electrically small split-ring resonators (SRRs) arranged in a cruciate pattern, each with a maximum dimension of less than lambda(o)/10, is shown to achieve more than 43% microwave-to-alternating current conversion efficiency at 5.67 GHz. Even-and odd-mode currents are realized in the proposed harvester to improve the efficiency and concurrently reduce the dielectric loss in the substrate. An experimental validation is conducted to prove the harvesting capability. (C) 2014 AIP Publishing LLC.