Anti-collision SAW tags based on CIDT

Many SAW RFID applications require the ability to read multiple tags located in close proximity, thus a structure of SAW tags based on CIDT is proposed to solve the “anti-collision” problem. Based on finite element analysis, the research of the CIDT-based anti-collision SAW tags is carried out by utilizing software COMSOL multiphysics. Primarily, the anti-collision unit of the SAW tags is studied from three aspects: the encoding method, the symmetry problem and the compatible code group of the CIDT. Then, the responses of the transducer-based SAW tags which consist of one input 7-bit Barker coded CIDT and four output IDTs in different correlation cases are studied. Furthermore, some improvement designs and extended applications of the CIDT-based anti-collision SAW tags are discussed. The simulation results show that the structure of the CIDT-based SAW tag makes it possible to solve the “anti-collision” problem for some RFID applications and can be easily combined with SAW sensors.