A Highly Efficient, Scalable, Tetra-Band Metamaterial-Based Ambient RF Energy Harvester

This article presents an innovative metamaterial-based radio frequency (RF) energy harvesting system designed to efficiently capture ambient RF energy across multiple frequency bands, including Wi-Fi (2.45 GHz) and 5G (0.9, 1.8, 2.1 GHz). Utilizing electric inductive-capacitive resonators and a rectification circuit, the system converts ambient RF energy into direct current (dc) power with high efficiency. Specifically, a single unit cell of the proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8 \times 8$</tex-math> </inline-formula> harvester is capable of generating up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$562~\mu $</tex-math> </inline-formula>W under an RF ambient power density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$40~\mu $</tex-math> </inline-formula>W/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. This high efficiency and scalability make it ideal for powering low-power Internet-of-Things (IoT) devices and sensors. The design emphasizes optimizing the unit cell to minimize computational complexity, enabling a more straightforward and scalable implementation. Experimental results demonstrate the system’s ability to efficiently harvest RF power across the specified bands, validating its potential as a sustainable solution for the growing power demands of IoT networks.