Research And Design Of Chipless RFID Tag Antenna

Radio-frequency identification(RFID)technology is an automatic identification technology which using radio frequency signal to achieve two-way information transmission.RFID has the advantages of non-contact,anti-pollution,durability,fast reading speed,high reading speed moving long reading range,various structure,rewritable,object identifiability and non-abrasion,compared to traditional magnetic card.Because of the potential market of chipless RFID tag for replacing barcodes,it has been the focus of research by experts and scholars in recent years.This paper researches the basic properties of all kinds of chipless tag through RFID system and the development and current situation of chipless tag firstly.Then we research the electromagnetic scattering theory and resonant mechanism of chipless tag.Next,three kinds of high encoding capacity chipless RFID tag antenna are proposed.Each has their own characteristics.Results in this paper can be summarized as follows.1.Studied the working principle of single open end U-shaped loop structure.Based on the theory of radar and back scattering,we proposed a dual-resonance chipless RFID tag antenna in which U-shaped loop is basic cell.The adjacent loops of chipless tag are connected by one stub line at the upper sides.The structure is designed to obtain the following function relationship between the loop number n and resonant mode number m:m(28)2(9)(n-1)(10)1.The data density of antenna is more than 14.66bits/cm~2.Simulation of the antenna works well.2.Based on the theory of radar and back scattering,we proposed a compact dual-polarized chipless RFID tag by using nested concentric square loops according to the requirments of dual-resonance and dual-polarized.The structure can realized dual-resonance and do not produce parasitic resonance.The structure is designed to obtain the following function relationship between the loop number n and resonant mode number m:m(28)2(9)(n-1).In the meantime,the structure of closed current ring make tag antenna magnetic and then the RCS magnitude is insensitive to the medium where it is pasted.We have studied the ID encoding technology through moving the stub line of antenna.Finally,we proposed a dual-polarized chipless RFID tag antenna according to the characteristic of line polarization.19 bits/cm~2 data density is obtained of the antenna,which is high according to the reported works.The measurment results of prototype of proposed tag match well with the simulated results.3.Based on the frequency domain encoding theory,a tri-resonance chipless RFID tag antenna is proposed accoding to the theory of radar and back scattering.Thes antenna design combines the working principle of square loop with single open end U-shaped loop.The structure is designed to obtain the following function relationship between the loop number n and resonant mode number m:m(28)3(9)(n-1).The encoding density of every encoding unit is more than 3bits.The data density of antenna with three U-shaped loops is more than12.62bits/cm~2.According to the simulation,the tag works well when it is pasted on bended surface.Finally,the measurment results of prototype of proposed tag match well with the simulated results.