Design And Research Of Broadband Antennas And Rectifying Circuit For MPT

With the rapid development of wireless communication technologies and Internet of Things technologies,there is an increasing demand for wireless charging of sensor terminal nodes.Microwave Power Transmission(MPT)is a method of using microwave radiation for energy transmission.It has the characteristics of high conversion efficiency,small environmental impact and long transmission distance.The microwave energy receiving system is the core part of the microwave energy transmission technology.It consists of a receiving antenna and a microstrip rectifier circuit,which determines the efficiency of the entire microwave energy transmission system.This paper summarizes the history and status quo of wireless power transmission system,and analyzes the relevant theories of wireless power transmission to design antennas with broadband&high-directionality,and rectifier circuit.And then verify its performance through physical testing.By analyzing the effect of the number of notches on the radiation edge and the position of the feed point on the bandwidth of the antenna,a wideband,high directionality radiating antenna is realized by combining the E type antenna and the U type antenna and changing the position of the feed point.The antenna which achieve a relative bandwidth of 50.8%,has a high directionality,and can be used as a transmitting and receiving antenna for a wireless charging system.By analyzing the effect of multiple patch antennas on improving the antenna gain and the influence of loading the parasitic patch on extending the antenna bandwidth,the feed network of the multiplexed patch antenna is improved to design a binary network patch antenna with differential feed network.The parasitic element is loaded above the radiating patch to increase the antenna gain while expanding the antenna bandwidth and effectively reduce the antenna's volume size.The measured antenna performance shows that the antenna can achieve a relative bandwidth of 41.3%,and has a gain of 9.1dB.At the same time,the volume is much smaller than that of ordinary multiple-radiant antennas.After analyzing various factors affecting the rectification efficiency of the microstrip rectifier circuit,the voltage double rectifier circuit is designed.Meanwhile,by designing the microstrip input filter,matching circuit and output DC filter,the rectifier circuit is realized.In the case of ultra-low power input power of 20dBm,the output voltage of rectifier circuit reaches 3.274V,which can drive the DC load with impedance of 1500.Through the performance test of the rectifier circuit's physical object,the circuit performance achieves the desired goal and can be used in a microwave wireless power transmission system.