Ambient RF Energy Harvesting System Based on Wide Angle Metamaterial Absorber for Battery-Less Wireless Sensors

In this paper, a wide - angle rectenna based on metamaterial absorber is proposed. By using the absorbing surface consists of multiple periodically arranged unit cells, the proposed ambient RF energy harvesting device can power sufficient DC power for a wireless sensor from the ambient RF sources in environment. The rectifiers employed in this rectenna system are optimized to have a RF-DC conversion efficiency of 38% and 50% at very low input power of -10 dBm and -5 dBm, respectively. The symmetric unit cells are designed to yield a high absorptivity at wide incident angle in both H plane and E plane and by attaching two rectifiers for each one of them, the device is able to achieve a wide - angle dual - polarized operation up to 140 degrees. Numerical simulations are conducted to validate the design while a comparison to previously introduced rectennas is also provided to elucidate the advantages of the ambient RF energy harvesting system in this work.