Research On Structure Of Chipless RFID Tag Based On Backscatter Signal

Compared with bar code recognition,RFID has the advantages of long distance recognition,high reading speed and strong penetration ability.At present,it is higher cost to restrict the widespread use of RFID.Chipless tags do not require silicon chips,so their production costs are lower than those with chip tags.Low cost chipless RF tags have become the most potential alternative to bar code,so chipless tag has become a hot spot of current research.This paper focuses on the design of chipless tag.First,According to electromagnetic scattering theory,a chipless tag backscattered signal model is established.Chipless tag structure is designed.In this paper,two kinds of tag structure are designed: 90 degree circular arc patch chipless tag and split ellipse ring patch chipless tag.From the basic resonance units of tag structure,the relationship between tag structure and frequency characteristics,the influence of excitation source on tag RCS,and the influence of media materials on tag RCS,two kinds of labels are analyzed respectively.Next,the tag is encoded.For the 90 degree circular arc patch chip less tag,the co-polarization component and the cross-polarization component of RCS is almost the same,we use the polarizing code to encode the co-polarization component and the cross-polarization component,and get the coding capacity of 16 bit.The 6bit coding digits are obtained by using wave peak coding for the split ellipse ring patch tag.Then,extract the poles of the scattered signal of the tag and identify the tag.On the basis of the matrix pencil method,a short time matrix pencil method is proposed to accurately separate the late-time response.By applying matrix pencil method to extract the poles and residues of the late-time response.Then the signal is reconstructed by the poles and residues.At last,comparing the reconstructed signal and the scattering signal,to verify the correctness of the pole extractionFinally,a ultra wideband antenna with dual notch functions is designed.The antenna has the potential to be used for the antenna of a chipless tag reader.