RF Energy Harvesting Antenna And Rectifier Circuit Design For Charging Management Applications

With the extensive application of Wireless Sensor Networks and the further research of modern wireless communication network technology,getting rid of the dependence on the original battery and the shackles of wired charging and realizing convenient and stable charging for low-power electronic products such as wireless sensor network node devices and intelligent mobile terminals has become a key problem to be solved urgently in the development of energy limited networks.Due to the uneven distribution of electromagnetic energy density in free space and the limited conversion efficiency of rectifying antenna which can harvest RF energy,the acquisition amount of RF energy is very weak.Rectifying antenna was applied to low power consumption electronic products,which has limited space.Rectifying antenna and power supply application circuit are studied and designed compactly based on RF energy harvesting.The compact RF energy harvesting and charging system circuit can harvest RF energy from free space and deployed RF transmitters at the same time,and store it in the energy storage element.Firstly,a three-frequency PIFA antenna for RF energy harvesting is designed in this paper.Based on PIFA structure,the working frequencies of 915 MHz,GSM1800 and 2.4G WIFI communication bands are realized through slot cutting.After fine-tuning antenna size parameters and feeding point position,its bandwidth is increased and antenna gain is improved.The RF receiving antenna realize three-frequency RF energy harvesting and achieve average 4d Bi gain.The antenna was processed with the model data obtained by simulation and tested in the RF energy harvesting system.The designed antenna performance for energy harvesting was optimized compared with that of the embedded patch antenna.Secondly,the Greinacher rectifier circuit with the impedance matching based on the three bands of 915 MHz,GSM1800 and 2.4G WIFI communication bands is designed.Greinacher rectifier circuit achieves rectifying efficiency of 56.8%,40.9% and 34.1% respectively under-10 dBm input.Rectifier circuit tested in the RF energy harvesting system,the three-frequency rectifying antenna can obtain the output voltage of 330 m V and 80 m V respectively on the 10k? load resistance at the distance of 3m and 4.5m from RF transmitters.Finally,a charging circuit based on BQ25504 power management chip is designed and the system circuit is tested.The harvesting and management of micro DC power supply energy is realized in this system circuit,which verify the feasibility of RF energy harvesting and charging system.