Research On Key Technologies Of Chipless RFID Coding

Chipless RFID tags have the advantages of not easy to damage,high recognition rate and less impact on the environment.In order to improve the reliability of chipless RFID tag identification and expand the tag encoding capacity,this paper has carried out in-depth research on the key technologies of chipless RFID coding.Through the combination of theoretical calculation and HFSS electromagnetic simulation,three methods for effectively reducing the electromagnetic coupling effect between coding units are obtained.These methods are used to design high-encoding density tags which can improve the recognition reliability,and use the composite coding technology to design chipless RFID tags with large coding capacity and small size.Mainly completed the following four aspects of work:1.Using U-ring resonator as the encoding unit,through the study of its electromagnetic coupling effect,three kinds of arrangement methods which can effectively reduce the electromagnetic coupling effect between resonators are obtained:horizontal offset of adjacent resonators,frequency interval arrangement of adjacent resonators,horizontal offset and frequency interval combination.The above three chipless RFID tag models are built with 12 U-ring resonators,and their recognition rate,electromagnetic field and surface current are simulated and analyzed.Make tag object and test its recognition effect.The simulation and test results show that the three methods can effectively reduce the electromagnetic coupling effect among the coding units of chipless RFID tags,thus significantly improving the reliability of chipless RFID tag recognition.2.Based on the research results of electromagnetic coupling effect among coding units,using I-slot resonator,arc resonator and U-ring resonator as coding units,the tag structure is improved by combining horizontal offset,frequency interval,horizontal offset and frequency interval,and three kinds of high-density chipless RFID tags of 20 bits,24 bits and 20 bits are designed,with coding density as high as 3.55 bits/cm2.The simulation results show that the reliability of reconstructed recognition of three high coding density tags designed in this paper has been significantly improved.3.Chipless coding method based on frequency spectrum characteristics was systematic researched.Frequency-shift coding technology is adopted,U-shaped slot resonator with high quality factor is selected as the basic structure of chipless coding,and 8 bits chipless RFID tag is designed using four nested U-shaped slot resonators.In order to improve the bandwidth utilization,dual-polarized bandwidth multiplexing method is adopted,and the size of the board is 20 mm*40 mm.The 16 bits tag is designed.The simulation and test results show that the decoding results are the same as the simulation results,and 65536 coding states can be achieved in the 2.7 GHz-5.4 GHz bandwidth.4.In order to further improve the encoding capacity,the frequency-shift encoding method is improved.The 9 bits tag is designed by using three nested concentric square slots,and the 18 bits tag is designed on the 27 mm*13 mm baseboard combined with the dual-polarized encoding method.The simulation and test results show that 262144 coding states can be achieved in the 4 GHz-10 GHz band.The results show that the three methods proposed in this paper can effectively improve the reliability of chipless tag recognition and solve the problem of high-density tag reconstruction.A resonator multi-bit coding is realized by using frequency shift and dual-polarization hybrid coding technology,which effectively improves the coding capacity of chipless tags and is expected to be applied in the field of chipless RFID.