Design And Printing Of Ultra High Frequency RFID Tag Antenna

Radio frequency identification(RFID)technology can implement the communication from tag to receiver without contact through inductive coupling or electromagnetic backscatter coupling.UHF RFID technology has the advantage of long communication distance,and can be used widely in the Internet of things.For RFID system,tag antenna is one of the core components for communication.The commonly used tag antenna is made of metal silver or copper,a nd the manufacture methods include etching,electroplating,winding,etc.However,the cost of the manufacture of antenna with metal as raw material is high,and the efficiency of common manufacture methods is low,and etching and electroplating will produ ce great pollution in the manufacture process.Given that,conductive paste with lower cost has been chosen as the antenna raw material.The UHF RFID tag antenna has been designed mainly based on the conductivity of raw materials,and then the RFID antenna with good performance has been produced by screen printing.In this paper,PET film is used as the printing substrate,and 40 wt.% silver paste and 70 wt.% silver-coated copper paste are prepared respectively.According to the performance of the paste,linear polarization antennas are designed by HFSS,and a circular polarization antenna is designed with 40 wt.% silver paste as raw material.The working chips of the two antennas are both NXP UCODE 7 UHF.The resonant frequency points of linear polarization and circular polarization antennas are 866 MHz and 915 MHz respectively.The antennas adopt multiple structural combinations to implement the impedance matching with the chip.Both antennas achieve omnidirectivity.For the linear polarization antenna,the comprehensive performance of the antenna made of silver paste is better than that of silver-coated copper paste antenna.Comparing the antennas using the same 40 wt.% silver paste,it is found that the linear polarization antenna has achieved high radiati on efficiency at the working frequency,and the radiation effect of circular polarization antenna shows good stability in the whole working frequency range.The antennas are prepared by screen printing using the corresponding raw materials during simulation,and the performance of the antenna s is tested.The test results show that the linear polarization antenna and circular polarization antenna achieve resonance at the working frequency and ha ve good impedance matching performance.Comparing the linear polarization antennas with different pastes,it shows that both the radiation efficiency and reading performance of silver paste linear polarization antenna are better than that of silver-coated copper paste antenna.Comparing different antennas with the same paste,it is found that the circular polarization antenna has better reading performance and high performance stability.On this basis,the preparation and performance test of circular polarization antenna are carried out with different conductive pastes.Among them,40 wt.% silver paste antenna realizes resonance at 915 MHz,and the reading distance at resonant frequency point can reach about 10 m.Therefore,considering the comprehensive performance and cost,the circular polarization antenna of 40 wt.% silver paste is chosen as the target antenna,and the preparation process is further optimized.This paper researches the influence of screen printing process parameters on printing quality,designs orthogonal test and analyzes the test results through SPSS.Then the optimal combination of screen printing parameters has been found out to improve antenna printing accuracy.Based on the opti mal printing parameters,PET,cck paper,printing paper and coated paper are used as printing substrates respectively.After that,the surface morphology and accuracy of the printing lines obtained under different conditions are analysed,and the performance of the antenna made on different substrates is tested.The test results show that the antenna based on coated paper has pretty good comprehensive performance,and the communication distance at 915 MHz can reach 12.4 m.The communication performance is nearly as high as that of the tag antenna based on metal,proving that the printing RFID antenna has a pretty good application prospect.