A Multiband, Polarization-Controlled Metasurface Absorber for Electromagnetic Energy Harvesting and Wireless Power Transfer

A multiband, polarization-controlled energy harvesting metasurface is presented in this article for harvesting electromagnetic energy in the Wi-Fi bands. Inspired by the split-ring resonator (SRR), a metasurface of SRRs is designed by nesting multiple SRRs together. The novelty of the design lies in the controllable multiband polarization and adjustable absorption frequency, so as to achieve the active modulation of energy harvesting on the metasurface at different frequencies. The metasurface is composed of a periodic array of SRRs unit cells, an impedance-matched rectifier, and a load. Metasurface arrays and rectifier integration are proposed to reduce power losses, while the channels formed by the array enhance energy density and improve the ability to capture energy. Moreover, the design for the rectifier is capable of rectifying RF energy from multiple Wi-Fi bands simultaneously at low input RF power density. The finite array of $5\times $ 5 SRRs absorber is fabricated and tested. Measurements in an anechoic chamber show that the fabricated prototype reaches the efficiency of 66.5% at 2.4 GHz, 40.6% at 5.2 GHz, 35.6% at 5.8 GHz under transverse electric (TE) polarization, and 38.3% at 5.3 GHz under transverse magnetic (TM) polarization when the incident power density is greater than 66 $\mu \text{W}$ /cm ² .