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The Design of RF Energy Harvesting and Transfer System

In this paper, the radio frequency (RF) energy harvesting and transfer system is proposed for low-power electronic devices. The RF energy harvesting system is designed for receiving 2.4GHz Wi-Fi signals, which is composed of four CPW fed hexagonal slot antennas and each one offers the bandwidth of 69.8% (1.4-2.9GHz) with a gain of 3.8dBi at 2.4GHz, a power divider, a 2.4GHz rectifying circuit without additional matching network and an super-capacitor. Through the measurement, the output voltage of the designed system can reach up to 1V. Subsequently, the RF energy transfer system is proposed and designed for transferring 433MHz RF signals. In this system, a helical antenna with the frequency from 426MHz to 447MHz is designed as the receiving antenna, and the T shape matching network is adopted to match the 433MHz rectifying circuit. Finally, the measured results demonstrate that the designed RF energy transfer system can drive a ZigBee sensor, a temperature and humidity instrument and an electronic clock, simultaneously, with a maximum diastance of 0.5 meter between the receiver and the transmitting antenna.