吳政忠臺灣大學：應用力學研究所張凱迪Chang, Kai-TiKai-TiChang2007-11-292018-06-292007-11-292018-06-292006http://ntur.lib.ntu.edu.tw//handle/246246/62499Devices based on surface acoustic wave (SAW) are applied to wireless communications, such as passive SAW based radio frequency identification tags (SAW RFID tags). They can be operated in some harsh environments. Due to the wireless capability, they are also suitable for remote monitoring and sensing. For SAW based RFID tags, the operating frequency and number of possible codes are both critical. In this study, the interdigital transducers (IDT) are operated in their higher harmonic modes to achieve to 915MHz. Moreover, a new idea of decimal coding scheme will be introduced to increase the number of possible codes. First, the Abbott’s coupling-of-modes model is used to simulated and analyze the frequency responses of SAW based RFID tags. Furthermore, inverse fast Fourier transform is applied to transform the responses into time domain. The information of tags is obtained and decoded. Using the simulation results, the three-finger IDT and double-electrode IDT are analyzed along with their harmonic responses, and the new idea of decimal coding scheme is also introduced. Finally, the SAW RFID tags with central frequency of 915MHz are fabricated on the 128°Y-X LiNbO3 using Nano/Micro-Electro Mechanical Systems (N/MEMS) techniques. The experimental result and simulation results are compared, and the new idea of decimal coding proof to be achieved. In conclusion, the study utilized the COM theory to analyze SAW based RFID tags. The tag with improvement decimal coding scheme can include more data bits, and has smaller die area (i.e. lower cost)Acknowledgements I Abstract II Lists of Notations III Table of Contents VII List of Figures IX List of Tables XI Chapter 1 Introduction 1 1-1 Research Motivation 1 1-2 Literature Review 2 1-3 Contents of the Chapters 3 Chapter 2 Analysis of SAW RFID Tags 6 2-1 Coupling-of- Modes Model 6 2-1.1 The Uncoupled Modes and the First-Order Wave Equations 7 2-1.2 Propagation Loss as a Perturbation to the Wave Equations 9 2-1.3 Electrode Reflections 10 2-1.4 Electrical Transduction 14 2-1.5 [P] Matrix 17 2-2 The Coupling-of-modes Parameters 21 2-2.1 Average Surface Wave Velocity Shift 22 2-2.2 Reflection Coefficient 23 2-2.3 Transduction Coefficient 25 2-2.4 Electrode Resistance and Electrode Capacitance 26 2-2.5 Attenuation Coefficient 27 2-3 The Simulation of SAW RFID Tags 28 2-3.1 Harmonic Excitation of IDTs 29 2-3.2 IDT Type Reflector 31 2-3.3 Programmable Reflector 33 2-3.4 Frequency Responses of SAW RFID 35 Chapter 3 Design and Fabrication of SAW RFID Tags 51 3-1 The Design of SAW RFID Tags 51 3-1.1 Decimal Coding Scheme of SAW RFID Tags 51 3-1.2 Design and Simulation of SAW RFID Tags 53 3-2 The Fabrication of SAW RFID Tags 55 3-3 Setup of SAW RFID System 56 3-3.1 Matching Network of SAW RFID Tag and Antenna 57 3-3.2 Setup and Measurement of Interrogation Unit 58 Chapter 4 Measurement Results 75 4-1 Measurement of SAW RFID Tags 75 4-2 Comparison between Simulation and Measurement Result 77 4-3 Comparison between Three-finger and Double-electrode IDT 79 Chapter 5 Conclusions and Future Work 89 5-1 Conclusions 89 5-2 Future work 90 References 921676741 bytesapplication/pdfen-US表面聲波式射頻識別標籤交指叉換能器高頻模態模態耦合模型十進位編碼微機電製程SAW based RFID tagsInterdigital transducerHigher harmonic modeCOM modelDecimal coding schemeN/MEMSthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/62499/1/ntu-95-R93543040-1.pdf