Research On Novel Miniaturized RFID Tag Antennas

Radio frequency identification(RFID)is a technology that reads information from an electronic tag attached to a target without contacting the target itself,which uses electromagnetic signal to exchange data.In the past several years,the attribute of RFID has made it an emerging topic for research as well as been widely used in supply chain management,smart space allocations to increase the efficiency.As the demand for deployment of large-scale RFID technology increases,more and more occasions require dense arrangement of RFID tags,miniaturized tags are demanded to fit this dense and compact installation environment.In this thesis,the research work about miniaturized UHF(Ultra High Frequency)tag antennas with high performance is presented as follows:1.A design methodology of two-armed planar helical antenna for RFID tag antenna is proposed.Parametric study on the structure of planar helical antenna is conducted.Then,a two-armed planar helical antenna with 1/4 turns is miniaturized by using the technique of folded line and software direct optimization respectively.Simulated and test results show that the gain of these two antennas is not less than that of the original antenna,as well as their size are about sixty percent and thirty percent smaller than that of the original antenna respectively.2.Several miniaturized tag antennas based on the split ring resonator(SRR)structure are proposed.The size of antennas is greatly reduced by using folded loops and capacitive loading techniques.Simulated and test results show that the good antenna gain is got,as well as the size of the proposed antenna is over sixty percent smaller than that of conventional SRR antenna with double split rings.3.A tag antenna based on the magneto-electric dipole is proposed.By combining a dipole with folded arms and a loop antenna,a novel directional tag antenna is presented.The simulation results show that the proposed antenna has good radiation characteristics with a peak Gain of 3.8dBi and a front-to back ratio of 8dB.4.The effect of dense tag environments on the performance of tag antennas is researched.A miniaturized planar helical antenna and a miniaturized SRR antenna are simulated and tested under dense tag environments.The measured and the simulated results show that there are no obvious effects on their electromagnetic behavior.