Research On Surface Acoustic Wave Based Radio Frequency Identification

The Internet of Things is a sign of the latest round of information industrial revolution. RadioFrequency Identification is one of the most important part of the Internet of Things. The RFID systemincludes tags and reader. The RFID technique based on surface acoustic wave is passive, it has longidentification of distance, can read out for high-speed mobile object and adapt to bad environment, soit becomes a hot research point in the RFID field.First, the thesis illustrates the principle of RFID system based on surface acoustic wave. Thentheory analysis of RFID system contains tag structure, encoded mode and the type of reader. The keypoints of this paper are the simulation, design, production and testing of SAW tag, the design oftransmit and readout unit of reader.Based on the finite element method, the surface acoustic wave tag is simulated using COMSOLsoftware. This paper build2D model for modal analysis. From the frequency characteristic simulation,the resonant and anti-resonant frequencies are extracted, analysing the cause of the error. On that basis,3D model is built, the influence of the inter-digital transducers metal electrode on the resonantfrequency is analyzed, analyses the influence of the inter-digital transducers aperture length on theexcitation efficiency and the amplitude-frequency curve is obtained. By the echo pulse characteristicsimulation, the different echo pulses corresponding on different reflector encodings are researched,the influence of the reflector metal electrode on the echo pulse is analyzed. The research results couldprovide guidance for the surface acoustic wave tag design and production.Based on the research conclusion of theory analysis and simulation，six groups of SAW tags aredesigned. The frequency characteristic, reflector encodings, excitation efficiency of IDT and printeddipole antenna are experimentally test through the network analyzer. The experimental results provethat it is effectiveness for theory analysis and simulation.A novel SAW RFID reader based on the time domain sampling is made out and progressed in thispaper. The reader contains control module, transmitter module and receive module. The control moduleof the reader is realized by ARM. Transmitter module is made of local oscillator, power amplifier andRF switch. The signal modulation and transceiver isolation are achieved through modulating signal byARM. Therefore, the circuit is simplified and the interference is decreased. The transmission circuit ismade of local oscillator chip ADF4350, power amplifier chip PA2460and RF switch chip AS177. Theexperimental results prove that the hardware circuit meets the requirements. Then the receive module is designed by using zero IF integrated receiver chip MAX7033.Finally, the thesis summarizes the research work on the topic, points out the shortcomings ofresearch work and expects the further work.