Implementation of RF Energy Harvesting System with Efficiency Improvement by Using Metamaterials

This paper proposed implementing an RF energy harvesting system with efficiency improvement by using metamaterials. The system can store the energy and supply it to a load or sensor device in the IoT system. The microstrip rectenna and metamaterial structure were implemented to improve efficiency in the energy harvesting system at 2.4 GHz. The microstrip rectenna was composed of a microstrip antenna and a rectifier circuit to converts receiving RF signal into DC voltage. Two metamaterial types were applied to the energy harvesting system: 1) the artificial magnetic conductor type which designed to be placed behind the rectenna and 2) the multiple split-ring resonators with a negative refraction index which placed in front of the rectenna. The fabricated prototypes were implemented on an RF energy harvesting system to demonstrate that the metamaterials improved the system efficiency. The measurement showed that the efficiency of the energy harvesting system was improved by using metamaterial. The electric charging time on a capacitor was measured. It was found that the electric charging time in the case of the system with AMC and MSRR structures was faster than the one without metamaterial structures.