Characteristics Simulation Of The Surface Acoustic Wave Radio Frequency Identification Based On A ZnO Single Crystal

Radio Frequency Identification(RFID) technology reads data by querying the target radio signals. Through the radio frequency signal's spatial coupling, the RFID could transmit and identify the related object data. Surface Acoustic Wave(SAW) RFID reader system consists of a reader, a SAW tag and a terminal data processing system. The SAW tag is made from a piezoelectric substrate on which a label antenna, reflective grating and an Interdigital Transducer(IDT) are fabricated. The SAW tag is a kind of RFID tag without chip, in which the IDT transforms the high frequency pulse into a surface acoustic wave and the SAW propagates in the crystal surface. The SAW tag is passive and easy to be put into mass production, also, it has some other advantages such as long distance identification and adapting to the harsh environment. The SAW tag is now widely used in the intelligent highway charge systems, vehicle anti-theft identification, freight management network systems and supply chain management. It is a good complementary tag with the electronic chip IC tag.ZnO single crystal attracts intensive attention from the domestic and international research institutions due to its high photoelectric coupling coefficient, low temperature coefficient, easy available and inexpensive. Up to now, there are few reports about the SAW tag based on zinc oxide single crystal.In this paper, based on the working principle of the radio frequency identification system, the characteristics of the ZnO-based radio frequency tag were studied by the use of COMSOL software.A multi-physical field coupled model was constructed and simulated. A model diagram was obtained and the 268 MHz positive eigenfrequency of and 275 MHz inverse eigenfrequency of the ZnO-based surface acoustic wave were extracted. The phase velocity of 2715 m/s was calculated through the simulation of the eigenfrequency. By the analysis of the frequency response, the relationship between the tag displacement and frequency was obtained and also the amplitude frequency characteristic was achieved. The effect of the IDT's structure on the radio frequency tag's eigenfrequency was analyzed. Finally, the effect of pulse amplitude code on echo pulse was discussed.