Broadband RF energy harvesting system covering CDMA, GSM900, GSM1800, 3G bands with inherent impedance matching

Abstract

A broadband RF energy harvesting system for harvesting energy from 800 MHz to 2.5 GHz is presented. A passive voltage amplification scheme and inherent matching technique using higher antenna impedance is employed to enhance the output voltage of the rectifier. A planar broadband folded dipole antenna having an input impedance of 300Ω is designed and fabricated. The measured VSWR is less than 2 from 825MHz to 1.27GHz and 1.67GHz to 2.17GHz. A RF energy harvesting system consisting of the high impedance antenna, Schottky diode based rectifier and a self oscillating boost converter is used to charge a 12µAh battery to 3.8V. At 844MHz for a received power of −10.7dBm the battery charges to 3.8V. At 1.73GHz the battery charges to 3.8V for a received power of −5.72dBm. Also using the designed RF energy harvesting system, a voltage of 4.4 V is measured for a load of 3 kΩ at 10 cm from a cell phone making a call.