Design And Implementation Of Radio Frequency Energy Harvesting System Based On Textile Microstrip Antennas

With the development of science and technology,intelligent wearable products with different functions appear in people’s life,and the power supply problem is also paid more and more attention.The traditional battery power supply not only needs frequent replacement but also causes environmental pollution.In recent years,with the rapid development of the Internet,there is a large amount of radio frequency energy with stable sources in the environment.Collecting radio frequency energy in the environment to solve the power supply problem of wearable products has gradually become a hot topic.The radio frequency energy collection system can convert the radio frequency energy in the environment into electricity through the receiving antenna and rectifier circuit,and solve the power supply problem for low-power intelligent wearable products.In this study,based on the background of the radio frequency energy collection system,textile microstrip single element antenna and array antenna with polyester felt as antenna substrate were designed.The high-frequency current received by the antenna was converted into direct current voltage output by the rectifier circuit,which realized radio frequency energy collection and voltage output in the external environment.The specific work of this study is as follows:(1)The design of textile microstrip single element antenna and array antenna with excellent performance.The side-fed textile microstrip single element antenna and 2×2 array antenna were designed by electromagnetic simulation software.The simulation and optimization results showed that the resonant frequencies of both the textile microstrip single element antenna and the array antenna were within the working frequency range,the radiation pattern was ideal,and the maximum gain at 0° was higher than 6d B.(2)Antenna preparation and performance test.The two antennas were fabricated by screen printing method.The samples were observed by scanning electron microscopy.The printing effect was good and the silver paste was evenly and tightly attached on the surface of the polyester felt.The performance-tested of the two antennas showed that the resonant frequencies of the two antennas met the requirements of the working frequency band.The return loss at the frequency of2.45 GHz was-23.05 d B and-18.53 d B,and the gain was 6.37 d B and 10.90 d B,respectively,meeting the performance requirements of the antennas.(3)Design and test of radio frequency energy collection system.The rectifier circuit working in the 2.45 GHz frequency band was designed and manufactured.The measured results of the rectifier circuit were basically consistent with the simulation results,and the return loss values in the 2.45 GHz frequency band were all less than-10 d B,meeting the working requirements.A WIFI router working in the 2.45 GHz band was used as the signal transmitting source to carry out systematic tests on the designed microstrip antenna and the rectifier circuit.The results showed that the output on-load voltages at both ends of the rectifier circuit connected with the microstrip single element antenna and array antenna were 9.7m V and 35.6m V respectively,which met the power supply requirements of low-power smart wearable products.