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 $8 \times 8$ harvester is capable of generating up to $562~\mu $ W under an RF ambient power density of $40~\mu $ W/cm². 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.