Design, fabrication, and characterization of an electromagnetic harvester using polarization-insensitive metamaterial absorbers

Increasing interest has been paid to metamaterial (MTM) absorbers owing to their huge potential in energy harvesting. However, only a few existing absorbers have the ability to harvest energy from arbitrarily polarized waves without assigning diodes to each unit cell, limiting their applicability and lowering the overall efficiency. In this work, we present an electromagnetic (EM) harvester based on MTM absorbers with the capability of doing so. The harvester consists of periodically arranged symmetrical MTM unit cells and two distinct power combiner networks, allowing it to efficiently harvest the power of incident EM waves with random polarization. With an absorption reaching 99%, the absorber possesses the EM-to-alternating current efficiencies of 75% and 78% corresponding to the vertical and horizontal polarization, respectively, while the final EM-to-direct current conversion efficiency can reach up to 55% at an incident power density of 350 mW m(-2). The MTM absorber can also be upgraded to incorporate more unit cells, forming a larger structure with an increasing amount of power harvested.