Research And Design Of Big Capacity Chipless RFID Tag

With the development of the 5G standard and the release of the first 5G chip,5G technology is about to enter the large-scale commercial stage.The Internet of Things(IOT),as one of the 5G application scenarios,has received increasing attention.Radio Frequency Identification(RFID)is an important part and key technology of the IOT.It can store information,easy to carry,flexible and reliable,and its unique identification and tracking capabilities in real-time asset monitoring,item and animal tracking have great application value in all fields.However,traditional RFID tags have high costs due to its chip and cannot be applied to the large-scale deployment of IOT.Therefore,chipless RFID tags with cost advantage have become the focus of current research.This dissertation was supported in part by the National Natural Science Foundation of China under Grant 61372008,and in part by the Science and Technology Planning Project of Guangdong Province under Grant 2014A010103014,2015B010101006,and mainly investigates big capacity of chipless RFID tags at UWB bands.The main works include as follows:(1)Dual-polarized high-capacity chipless tag: A big capacity dual-polarized(DP)chipless tag is proposed for UWB band.By using arrow-shaped slots embedded in a rectangular patch,the current path is extended and the size of tag is reduced.At the same time,the DP operation is achieved by placing slot elements symmetrically in both main-diagonal(MD)and vice-diagonal(VD)polarizations.The final size of the tag is 15 mm × 15 mm × 0.5 mm,and the coding capacity is 24 bits,which is characterized by small size and big capacity.In addition,a unique two-factor encoding technique is designed to enhance the robustness of the tag and improve the accuracy of tag identification.In this paper,the coding method,working principle and performance of each parameter are analyzed.Finally,the tags have been fabricated and measured,and the actual results is basically consistent with the simulation.It can be seen that the designed dual-polarization tag can be coded accurately and has practical use value.Due to the DP tag is sensitive to polarization,the mismatch occurs after the tag rotates beyond a certain angle,resulting in recognition errors and even unrecognized.For this reason,this paper proposes an omnidirectional DP chipless tag based on angle positioning.(2)Omnidirectional DP chipless tag: The tag is based on the previous tag,an I-shaped slot for angular positioning was added at the bottom of the tag to allow real-time positioning of the tag rotation angle.At the same time,according to the mismatch range of the tag and the error of positioning,the entire reading area is divided and the omnidirectionality of the DP tag is finally realized.The tag still has a big capacity and its size slightly increases to 15 mm × 16 mm × 0.5 mm.Moreover,we apply the chipless MAC protocol to the designed omnidirectional identification process and use the angular positioning frequency as the preamble frequency to save the reader's recognition power and time.The tags have been fabricated and measured to verify the accuracy of the angle-based localization technology,which overcomes the polarization-sensitive problem of DP tags,and further increase the practical application value.(3)Chipless tags for long range identification: Since the chip is removed,the tag becomes a completely passive device.So the signal transmitted by the tag is weak,easy disturbed by the ambient noise and the range of identification is low.To solve this problem,the segmented ring structures are first loaded on the previous tag,improves the RCS of the original tag.Then we propose a fan-shaped chipless tag,which can be merged into a circle to greatly increase the RCS amplitude,thereby increasing the tag's recognition distance.The designed fan-shaped tag's size is 26 mm(radius)× 0.15 mm(height),and the coding capacity is 14 bits,with omnidirectional characteristics.The UWB big capacity chipless tags developed in this paper have high capacity density,suitable size,and strong robustness.The tag has omnidirectional characteristics and large RCS amplitude,which makes the designed tag have higher practical value.It is hoped that through the big capacity tag research in this paper,we can provide a reference guideline for chipless tag design.