Research On Chipless Tag Structure And Spectral Pulse Position Modulation

Radio Frequency Identification(RFID)is a non-contact target recognition and detection technology,which has the advantages of fast identification,non-visual reading,long identification distance and reusable.However,the traditional radio frequency identification technology needs electronic tags containing silicon chips,which is expensive,which limits the further development of radio frequency identification technology.Chipless Tags do not need silicon chips.They are easy to fabricate and inexpensive.They have become a hot research topic.However,the current chip-free tags have some shortcomings,such as low coding capacity and low coding density.This paper focuses on the design of coreless tags with large coding capacity and compact structure,and uses spectral pulse position modulation to enhance coding density.Firstly,a triangular chipless Tags is designed based on spectral pulse existential modulation(OOK)coding,which can achieve 12 bit coding capacity.Because of the high symmetry of the label itself,the RCS response of the label is not affected by the polarization angle of incident wave.In order to improve the coding density,the triangle label is cut in half to form a butterfly tag.the coding capacity of 10 bits can be achieved.The butterfly-shaped chip-free label was fabricated and tested by vector network analyzer.The label has obvious resonance characteristics and can achieve the purpose of coding.Then,the spectral pulse position modulation coding(PPM)code is studied.Firstly,the chip-free label based on I-shaped single dipole is studied.Controlling each resonator can correspond to four resonant points,and using four resonators can achieve 8 bit coding capacity.C-shaped folding dipole without chip label,it has smaller surface area.If a resonator allocates more resonant points,the coding density will be higher if PPM modulation is used.In this paper,a new PM modulation method based on permutation and combination is proposed.The coding capacity can be increased by three times.Finally,the U-shaped bipolar chip-free label PM modulation is studied.The limited spectrum can be reused twice to obtain larger coding capacity.Firstly,the single U-shaped bipolar tag is studied.one resonator corresponds to 10 resonance points,vertical polarized resonator tag is used to represent 10 bits,horizontal polarized resonator is used to represent one bit,and two resonators can realize 100 decimal coding.In order to improve the coding density of tags,dual-polarization chipless tags with U-shaped nested structure are studied,and the coding capacity is further improved.