Chipless RFID system for barcode replacement

Radio Frequency Identification (RFID) is a modern wireless data transmission and reception technique for applications including automatic identification, asset tracking and security surveillance. As barcodes and other means of identification and asset tracking are inadequate for recent demands, RFID technology has attracted interest for applications such as logistics, supply chain management, asset tracking, and security access control. However, the cost of RFID limits their potential for the replacement of trillions of barcodes each year. The only possible solution is a fully printable chipless RFID tag. A novel RFID system comprised of a chipless RFID tag and an associated reader is reported in the thesis. The chipless tag is a fully-passive microwave circuit and uses spectral signatures for data encoding. The tag consists of a multi-resonator coupled to transmitting and receiving antennas. To accommodate multiple bits, the tag operates over the ultra wideband (UWB) frequency spectrum. UWB antennas are used to receive the interrogation signal sent from the reader and transmit the signal back to the reader after performing modulation of the frequency spectra with the multi-resonator. Modulation is performed in both amplitude and phase of the spectrum. A chipless tag up to 35 bits which operate over 3-7 GHz band has been designed. After the successful design of the chipless tag, three prototype readers have been developed. The Gen1 reader was designed to validate the chipless RFID concept using 6-bit chipless tag reading based on amplitude-only detection in S-band; the Gen2 reader is an upgraded version of Gen1 with both amplitude and phase detection capability; and the third generation reader is a UWB reader capable of reading up to 35-bits in the UWB band. The integrated reader is a complete system with analog RF and digital control sections loaded with graphical user interface (GUI) and software protocol. Both the hardware and software design of the RFID reader and field trials of the designed chipless RFID system have been validated in the real world environment. An investigation into antenna systems in order to enhance reading range up to 70 cm has also been performed. The unique features of the developed chipless RFID system are: (i) a low cost, fully printable tag and (ii) secure, remote and non-line-of-sight operability. The importance of this concept lies in the fact that chipless RFID tags become comparable to barcodes in terms of the substrate material used and the cost of fabrication. The main application of this chipless RFID system is in short-range tagging of extremely low cost items such as the Australian polymer banknote.