Design Of Surface Acoustic Wave Id-tag Based On Radio Frequency Identification

Nowadays there are many automatic identification technology,such as Radio Frenquency Identification(RFID), Bar Code, Optical Character Recongnition(OCR),Voice Recognition, Biometric Identification. Magnetic card, IC card etc. RFID is a non-contact automatic identification system for data communication which is based on RF and mrcirowave principle.SAW-Tag is, a kind of RFID-Tag, using Surface Acoustic Wave technology ang having more advantages.Compared with Bar Code,SAW-Tag is unrestricted with the size and configuration of object,visible and easily damaged restrain. Compared with IC-Tag,SAW-Tag can be used on metallic objects at high tempreture(-100℃~300℃) and electromagnetic enviroment.need photoetching once.less process and cost.Content of this dissertation covers theories of RFID and SAW,compositon and working principle of SAW-Tag,designs of ZnO/Diamond layerd structure,Antenna,Mtching Metwork between tag ang antenna,the main work is as follows.SAW-Tag analysis is discussed usingδfunciton and equivalent circuit model.With Matlab, we analysis the frenquency response,resert loss of IDT,the influence of the change of N and W to SAW-Tag system.ZnO/Diamond layerd structure has four structures: (a)ZnO/IDT/Diamond/substrate (b)Metal layer/ZnO/IDT/Diamond/substrate (c) IDT/ZnO/Diamond/substrate (d) IDT/ZnO/ Metal layer/Diamond/substrate.So there are four kinds 50? tags working at 2.5GHz.Antenna is needed to work with SAW-Tag for wireless communication.Impedance matching is the main key question for most power transmission.We have designed two kinds of matching network: LC resonnat circuit and equivalent mrcrostrip lines.A printed dipole antenna woking at 2.5GHz is designed with ADS,bending the aibretor arm to miniature size.The final size is 33mm×30mm.The input impedance is 50?.Return loss is -24.371dB,VSWR is 1.146,Gain is 1.448 dB,impedance bandwith is 22.6%.