Design Of Chipless RFID Tags Based On FSS

As a new technology in the information age,the Internet of Things has a very broad application prospect.Among them,radio frequency identification(RFID)will play a major role as the core technology of the Internet of Things.Since ordinary RFID tags contain chips inside,the cost is high,which limits their large-scale applications.Chipless RFID tags solve the cost problem and have great market potential,and have become one of the research hotspots of RFID technology.Based on the principle of frequency selective surface(FSS),this paper uses Ansoft HFSS 15.0 software simulation combined with physical testing to conduct in-depth research on chipless RFID tags with large coding capacity,strong environmental adaptability and compact structure1.A U-H chipless RFID tag was designed using the principle of frequency selective surface.U-type and H-type resonator models are constructed respectively,and the influence of main structural parameters on their resonance performance is simulated.The two resonators are combined into a U-Htype coding unit,and the double adjustment of the U-type and H-type resonators is carried out.A variety of offsets of the frequency are implemented,and 12 coding states and their corresponding coding criteria are determined.On the 25mm×30mm substrate,four U-H resonators of different sizes are arranged side by side to form a tag,and the tags of different coding states are simulated to verify the reliability of the identification.The results show that the tag can identify 14bits in the frequency range of 3GHz～10GHz.In theory,20736 encoding states can be distinguished,and the effect of large-capacity encoding is realized by a small number of coding units.2.In order to adapt to the complex electromagnetic environment,an octagonal shape that is insensitive to the polarization angle is used as the tag structure,and a compact frequency selective surface chipless tag is designed.An octagonal slot single-ring resonator model is constructed,and the influence of side length and width on its resonance performance is simulated.A plurality of octagonal FSS resonators are formed into nested units,and the appropriate interval is determined by simulating the spacing.The polarization insensitivity is verified by different polarization angle incidence simulations.Ten octagonal gap rings are nested to form a chipless tag.The reliability of the code is verified by reconfiguring the tag.The designed label was physically tested.The test results showed that the tag working frequency range was 2GHz-6GHz,and 1 Obits encoding was realized on the 30mm×30mm size substrate.3.In order to make the tag encoding capacity larger,the principle of dual polarization is applied to the tag design.By using horizontally polarized wave and vertically polarized wave to illuminate the 1/4 octagonal slit ring resonator,it is verified that it has single polarization characteristics,and 10 1/4 octagonal gap resonators are horizontally vertically nested.The array is arranged to be a dual-polarized RFID chipless tag;the tag is encoded with the presence or absence of resonance,and the combined ID of the vertical polarization ID and the horizontal polarization ID is used to double the coding capacity;the tag is reconstructed The simulation verified the correctness of the different ID identification;the physical test of the designed tag showed that the tag working frequency band was 3GHz-8GHz,and the current 20bits encoding was realized on the substrate size of 30mm×30mm,and the encoding density was as high as 2.22.Bits/cm2.