Design Of 2.45/5.8GHz RF Energy Harvester

This work proposes a dual-band RF energy harvester operating frequency at 2.45GHz and 5.8GHz.The antenna is used for receiving signals from the RF energy transmitter or capturing RF energy in the surrounding environment,and thereby providing input power to the rectifier circuit.The function of the matching network is to achieve conjugate matching between the rectifier circuit and the receiving antenna,so that the energy collected by the antenna can be fully utilized by the rectifier circuit to achieve maximum rectification efficiency.The rectifier circuit is applied to rectify the received RF signal and fed to a Schottky diode to power the load.This paper designs RF energy harvester from the following aspects.1.The research status of RF energy harvesting technology,the technical problems and new development directions that need to be solved are investigated.Based on the composition and working principle of the RF energy harvesting system,the design method of the receiving antenna is discussed.By comparing and analyzing several common rectifier circuits,the appropriate rectifier circuit structure is selected.2.Combined the inverted L-type and Hilbert curve structure,a miniaturized dual-frequency monopole microstrip antenna with a center frequency of 2.45GHz and5.8GHz is proposed.The antenna is made of FR4,and its dimensions are 18.9mm×15.4mm×1.6mm.The simulation results show that the bandwidths of the antenna at the two center frequencies(S₁₁?-10dB)are 50MHz?2430²480MHz?and 360MHz?5630⁵990MHz?,respectively.Aiming at the low gain and low working bandwidth of the antenna at low frequencies,an improved small dual-frequency monopole microstrip antenna with a gain of 1.66dBi and 4.03dBi at 2.45GHz and 5.8GHz is designed.The low-frequency relative bandwidth is 8.57%?2.37².58GHz?,and the high-frequency relative bandwidth is 15%?5.46⁶.33GHz?.3.A fan-shaped straight-through filter,a multi-stage Schottky diode rectifier and a dual-frequency impedance matching circuit are designed.The ADS software is used to simulate the characteristics of the diode.The effects of diode type,rectification structure,capacitance,load and rectifier circuit order on the rectification efficiency and output voltage of the rectifier circuit are studied.The simulation results show that the maximum rectification efficiency of the rectifier circuit at 2.45GHz and 5.8GHz is 60.4%and 35.5%,respectively,when the input power is 10dBm.4.The physical welding,debugging and circuit performance test of the rectenna are conducted.When the input power is 10dBm,the output voltages of the voltage doubler rectifier circuit at 2.45GHz and 5.1GHz are tested to be 4.69V and 1.94V,respectively,and the maximum rectification efficiency is 27.5%and 4.7%,respectively.At the end of the paper,the shortcomings of this design are summarized.Finally,the future improvement direction is proposed.