Ambient RF power harvesting: Application to remote supply of a batteryless temperature sensor

This paper deals with the design and experiments of an efficient rectenna circuit, operating in the ISM band at 2.45 GHz, intended to remotely supply a batteryless temperature sensor. More than 80% efficiency is experimentally achieved at medium and low power densities. The circuit contains a symmetric and dual-access RF-to-dc rectifier and 2 patch antennas. The temperature sensor performs measurements every 10 seconds and requires 1 V voltage and 30 μJ energy per period. It operates from low power densities of only 0.4μW/cm2 (E = 1.22 V/m).