Metamaterial absorber-based rectifier circuit for efficient RF energy harvesting at 2.4 ghz for IoT applications

The radio frequency (RF) energy harvesting system collects electromagnetic energy that is freely propagating in the environment to charge low-power devices. In this study, we propose a novel voltage rectifier circuit based on a metamaterial absorber. Radio frequency energy in the 2.4 GHz ISM band is harvested from the environment by a metamaterial absorber and converted into direct current (DC) energy in a rectifier circuit. First, a high-efficiency metamaterial absorber of size 34 mm x 34 mm x 1.6 mm is designed on an FR4 substrate, followed by the design of a voltage rectifier circuit. The metamaterial absorber operates in the 2.4 GHz ISM band and is designed using a Finite Integration Technique (FIT) based simulation program that provides parametric and genetic algorithm tools. The design achieves a Reflection Coefficient \(\:\left({\text{S}}_{11}\right)\) of -26 dB and an absorption value of 99% at a working frequency of 2.4 GHz, independent of polarization direction. The voltage rectifier circuit is designed using Advanced Design System (ADS) software, and it achieves an efficiency of 73% for 5 dBm input power at 2.4 GHz. The designed metamaterial absorber structure and rectification circuit have been fabricated in the laboratory, and the simulation and fabrication results are consistent. The energy harvesting system presented in this study can generate electrical energy to power low-power Internet of Things (IoT) devices at a voltage of 1.9 V DC.