الفهرس 
CHAPTER 1: IntroductionOnly 14 pages are availabe for public view
 |  | from | 167 |  |  |
| | | from | 167 | | |
Abstract
This thesis addresses the design of the chipless RFID tag, which is used to encode data into the tag’s spectral signature. Earlier data encoding technique using spiral shorting is presented. A multiresonating circuit comprised of cascaded spiral resonators used to encode data into the spectral signature is designed and optimized. Chipless RFID tags require a significant amount of spectrum in order to encode their data. Hence, ultra wideband antennas seem like the obvious solution as the antenna of choice for the chipless RFID tag. This thesis presents a new radio frequency identification chipless tag operating in the frequency range of 4-7 GHz. The tag consists of triangle microstrip filters. The bits are encoded into the spectrum hence the tag has a unique spectral signature. A 6-bit chipless tag is designed. The simple opening of the triangle sides shifts the resonant frequency of the triangle resonator to a frequency outside the designed band. The effect of curvature on the characteristics of the filter is investigated. The chipless tag is designed for advanced traffic and vehicle regulation, alarm and navigation. Another chipless tag operating in the frequency range of 3.5-4.3 GHz is considered. It focuses on the integration of the antenna and multiresonator structures to form the chipless RFID tag. The tag consists of triangle microstrip filters with cutting slots in the triangle sides. A 6-bit chipless tag is designed. The bits are encoded into the spectrum hence the tag has a unique spectral signature. The chipless tag is comprised of a vertically polarized circular UWB microstrip monopole receiving tag antenna, a multiresonating circuit and a horizontally polarized circular UWB microstrip monopole transmitting tag antenna. The multiresonating circuit is designed by cascading triangle resonators next to the microstrip line with different positions of cuts in the triangles sides so that a multiple resonances occur. The simple opening of the triangle side shifts the resonant frequency of the triangle resonator to an out of band frequency, which is not used in the tag resonators band. Each resonance is separated by approximately 100 MHz from each other. Another tag is made of two rectangular patches loaded with multiple slot resonators of different
Abstract
resonances. This tag can be printed cheaply on one side of plastic or paper-based items like ID cards, banknotes etc.
This tag does not have a ground plane and has single sided compact tag with higher data capacity and lower cost compared to the existing printable chipless tags. A compact printable orientation independent chipless RFID tag is presented. The tag consists of a circular patch loaded with multiple semi-circular slot resonators. This symmetric frequency domain based tag has the advantage to be read from any orientation with the reader antennas. In this thesis the tag consists of horizontally and vertically polarized shaped slot resonators. It can be used as an orientation independent linearly polarized tag at the half data capacity of the dual polarized setup. Slot semi-circular resonators of different diameters are used to create different frequency signatures. Fully printable low cost chipless RFID temperature sensor is presented. The integration of temperature sensing is performed by utilizing the resonant frequency of a specific slot of the tag. Unlike earlier reported works on chipless RFID temperature sensor our proposed sensor does not require any external circuitry or semiconductor chip for sensing environment temperature. Rather, it performs real time temperature sensing using the dielectric property of temperature dependent high εr polyamide material that introduced high εr dielectric material changes its permittivity with environment temperature. Results verify that a dedicated resonator can perform the sensing whereas the other cascaded resonators represent the ID of the tag. At the end optically transparent flexible conductive polymer antennas and tags for radio frequency identification systems are proposed. Conductive polymer antennas and tags are compared to antennas and tags with the same design fabricated out of copper.