Compact printable chipless RFID systems
2017-02-23T01:54:40Z (GMT) by
RFID tags have the potential to replace barcodes on account of their numerous advantages, such as long reading range, non-line-of-sight reading, and automated identification and tracking. However, due to their high cost compared to that of barcodes, the current chipped RFID technology has not yet gained wide acceptance, especially in the field of item-level tagging of cheap items, where trillions of tags are required. Currently, multi-bit passive chipped RFID tags are used for tagging only costly items, where the cost of the tag depends mainly on the used silicon chip. Therefore, previous research has focused on developing chipless and printable RFID tags, which can be used like barcodes. However, a compact and fully-printable chipless RFID tag with sufficient data capacity and orientation insensitivity has not been proposed to date. This motivated this research study. In this work, two different frequency domain based system solutions are proposed in the microwave frequency band as representatives of a new generation of chipless RFID systems, which are capable of dominating the RFID market in the future. The first one is a compact printable orientation insensitive (OI) system, which will overcome the fixed orientation reading limitation of most other chipless RFID tags. In this OI system, the proposed tags consist of a circular conductive patch loaded with multiple ‘O’ shaped slot ring resonators or a square patch loaded with symmetrically placed ‘I’ shaped slot resonators in all four sides. The second proposed system is a compact printable dual polarized (DP) system that will overcome the limitation of data capacity by doubling the encoding capacity. The proposed tags consist of conductive patches loaded with vertically and horizontally-polarized ‘U’ or ‘I’ shaped slot resonators. Commercially suitable reader antennas are then developed for both the OI and DP systems, where linearly polarized (LP) antennas are developed for reading the OI tags, and dual polarized (DP) antennas are developed for reading the DP tags. Moreover, guidelines are also provided for designing LP and DP antennas with new sets of specifications, which are used next to develop commercially suitable 4×4 and 8×8 LP arrays, and 4×4 DP array antennas in the millimeter (mm) wave frequency band for reading recently developed promising mm-wave tags. Finally, the architecture for a universal DP reader is proposed for reading the novel DP tags using the developed DP antennas, which is also capable of reading all existing LP, OI and cross polarized (CP) tags in the frequency domain. In the final phase of the research, practical implementation steps for the printable chipless RFID technology, such as, paper substrate characterization and tag printing procedure on the paper substrate are studied thoroughly. Thus, the outcomes of the research provide the compact and fully-printable chipless RFID systems, which can be used commercially for identification in item level tagging of the low cost items, as well as for authentication in the printable secure documents.