Research Of Chipless RFID Tag Identification Code Based On Complex Frequency Domain

Radio Frequency Identification(RFID)is a contactless and automatic technology for target detection and identification based on radio frequency principle.RFID System is composed of two major elements:tags and readers,in which the cost of the electronic tag is one of the most important restraints on the development of RFID technology.The chipless RFID tag scheme is a way to reduce the cost of the tag.And the way to achieve the goal of detection and identification has accordingly become the focus for the lack of information processing units in chipless RFID.This paper studies the detection and identification of chipless tag based on complex frequency domain.Firstly,we design a tag structure that reduces the coupling between the C-shaped scatters,reducing the frequency shift of the traditional C-shaped chipless tag and increasing the recognition accuracy of the tag with 15-bit code capacity.In addition,a diamond chipless tag embodying 10-bit code capacity is designed with its frequency domain response in the ultra-wideband(UWB)range.This structure has large code capacity,insensitivity to the polarization angle of the incident wave,and higher harmonics components of the interference.Secondly,based on complex frequency domain,this paper proposes a pole coding method,in which pole attenuation factor and complex natural resonance frequency information are jointly coded.After coding and analyzing the designed tag structure,we find that the pole coding performs well when the 15-bit code C-tag fails to recognize the information.So this method can well recognize diamond chipless tags with a 10-bit code capacity.Finally,the accuracy of the pole-coded identification of the chipless RFID tags under noise interference is analyzed.When the SNR is greater than 5d B,the pole coding method can accurately identify the given single-bit tag information.When the SNR is greater than 8d B,it can realize the accurate identification of diamond-shaped chipless tag with 10-bit code capacity.When detecting the number of multiple tags,it can implement the detection of multiple tags from detecting the number of attenuation factors in the complex resonant domain.