Study Of The Chipless Tag And Reader Antenna In RFID System

With the development of internet of things,the radio frequency identification technology,as the core technology,has been paid more and more attention.So the research of RFID tag and antenna is of great significance.In this paper,a V-shaped chipless tag is studied and a broadband and a dual-band endfire reader antenna are designed.1)A V-shaped chipless tag is studied.Its radiation unit is composed of two identical metal arms with an angle of ? between them.Tags are identified by measuring the backscattered field.Firstly,the backscattered field and identification of tag is studied when it is tilted or the angle between the transmitting and receiving equipment is changed.In case that identification error is less than 2?,the maximum inclined angle of the tag is 20?.Also,the angle between the transmitting and receiving equipment should less than 10?.Secondly,the scattering characteristics and identification method of the V-shaped chipless tag with the package layer is studied.Also,identification formula is improved.Based on it,the influence of the thickness and dielectric constant of the package layer on tag identification is studied.The measured and simulated results show that the improved formula can improve identification accuracy and the identification errors are less than 2?.2)A broadband endfire reader antenna used to identify chipless tag is presented.The proposed antenna is a quasi Yagi antenna consisted of three microstrip dipoles and fed with the balanced microstrip lines.By adjusting the size of the active dipole and directive dipole and making them resonate in the different frequency band,the antenna achieves a broadband.The simulated relative bandwidth is 87.5%(1.42 GHz-3.63 GHz)and the maximum gain is 4.02 d Bi.In order to identify the tag with smaller sizes,a dual-band endfire reader antenna resonating at 2.4 GHz and 5.2 GHz is designed.By introducing the dielectric substrate and metal patch under the broadband endfire reader antenna,the dual-band radiation is realized.Also,by eroding parasitic slot in the metal patch,the bandwidth at low frequency is broadened.The measured results indicate that the realized antenna has the bandwidth of 31%(2.31 GHz-3.09 GHz)and7.2%(5.0 GHz-5.37 GHz),respectively.The maximum gains at two bands are 1.81 dBi and 4.27 dBi,respectively.