Design And Research Of Environmental Radio Frequency Energy Collection System

With the development of the Io T(Internet of Things),self-powered electronic devices have attracted widespread attention.The RF(radio frequency)energy collection system that collects surrounding electromagnetic waves has also become one of the research hotspots.Starting from the basic architecture of the RF energy harvesting system,the paper designs and implements two energy harvesting systems,single-band and dual-band to collect WIFI and GSM signals in the surrounding space respectively,and achieve better results.First of all,the paper designs a single-band energy harvesting system based on WIFI signals,and realizes a single-band circularly polarized antenna by adding radiation patches on the top surface and loading slots on the bottom surface.The reflection coefficient of the antenna in the WIFI frequency band is greater than 25.65d B.The single-band rectifier circuit module is a single-stage voltage doubler rectifier circuit.When the load R_L=3k?and the input power is 9d Bm,the RF-DC conversion efficiency of the module can be up to 64%.The rectifier efficiency can be achieved even when the input power is-20d Bm.And it used the last stage of DC-DC booster to boost the collected DC voltage to 3.52V.Considering that GSM signals are also ubiquitous,on the basis of the above-mentioned single-band energy harvesting system,a dual-band energy harvesting system of GSM and WIFI is designed and implemented.The system includes a circularly polarized antenna for GSM-1800 and WIFI frequency bands and a dual-band rectifier circuit module.The-10d B bandwidth range of this antenna is 1GHz-2.6GHz.The dual-band rectifier circuit module is realized by a designed matching network.The bandwidth of this module can cover the mobile downlink frequency band and WIFI frequency band in GSM-1800.When the dual-frequency input power is 7.5d Bm,the maximum RF-DC conversion efficiency is 53%,and the output DC voltage is 1.73V.Two RF energy harvesting systems placed near the working router can light up LED lights to achieve their energy harvesting function through testing,but the efficiency of the dual-band energy harvesting system is higher than that of the single-band energy harvesting system.Super capacitors can also be used to store the energy collected by the dual-frequency energy harvesting system.The maximum voltage that can be stored is 0.702V.