Research And Design Of Chipless Radio Frequency Identification Tag

The Internet of things(Io T)has been listed as one of the five emerging strategic industries in China and written into the "government work report".It has good market benefits and will become the next trillion industry.One of its core technologies is Radio Frequency Identification(RFID)technology.However the high cost of electronic tags limits their scope.Chipless tags provide a new solution to reduce the cost of electronic tags and have become a research hotspot.This dissertation studies and designs a series of chipless RFID tags,mainly including the following contents:In chapter 2,an angle-based slot-loaded linear chipless RFID tag is presented.The scatterer of the tag is a linear patch,and two L-shaped slots of different lengths are loaded on the patch.The tag is identified by measuring the scattered field in two orthogonal polarization directions.The angle formed by the linear patch with respect to the incident wave electric field is used to encode.One element of the proposed tag can carry 9.7 bits of information.Simulated and measured results show that the angles can be identified and the identification errors are less than 4.1°.The linear chipless RFID tag can also be used as an angle sensor.Next,an angle-based V-shaped chipless RFID tag is presented.Its scatterer is v-shaped patch and the angle between two arms is coded using space angle.The tag can carry 3.32 bits of information.Simulated and measured results show that error is less than 2.9°.After that,the scattering characteristics and identification method of the V-shaped tag with two elements are also studied.The proposed two kinds of tag are both measured in a real environment,not in an anechoic chamber,which indicates that the designed tags have strong anti-interference ability and practical value.In chapter 3,a chipless RFID tag based on frequency domain coding is proposed.Its scatterers are designed to be 6 L-shaped patches of different sizes which can carry 6 bits of information.The proposed tag is identified by measuring the backscattered field in the cross-polarization direction.In order to increase the reading distance and improve the tag robustness in harsh environment,the L-shaped patch was repeated for 8 times.The simulation results show that,the backscattered field after repeating is 5 times stronger than that of a single scatterer.As a result,the designed tag could be detected when the environmental noise is large.To validate whether the tag can be efficiently detected on metallic platforms,the tag with an increased ground plane is simulated.The results show that the backscattered field in the cross-polarization direction is stable and the tag can still be detected on metallic platforms by the backscattered field in the cross-polarization.In chapter 4,a novel hybrid coding chipless RFID tag based on space angle and spectral domain is presented,which has high coding capacity.Its scatterer consists of one horizonal linear patch(l0)and 9 vertical linear patches(l1-l9).The tag encodes data based on spectral domain by changing the interval d between vertical patches(i.e.,the length of the horizonal linear patch)and the absence/presence of vertical linear patches,which encodes 12.2 bits of information.In this case,it uses the frequency bandwidth of 330 MHz(1.23-1.56 GHz)and 1.52 GHz(1.89-3.41 GHz)respectively.At the same time,the tag encodes data based on space angle ? between the horizonal linear patch and incident electric field,which realizes 19 coding states and encodes 4.2 bits of information.In such a situation,no extra frequency band is occupied.Simulated and measured results show that one scatterer of the tag can carry 16.4 bits of information,while the tag area is only 6 × 6 cm~2,and the encoding density can reach 0.46 bits/cm~2.Compared with the above linear tag or V-shaped tag described in chapter 2,the encoding capacity of the tag is improved greatly.