Design And Research Of RFID Tag Antenna For Platform Tolerant Applications

Radio frequency identification(RFID) technology is an automatic identification technology that has developed rapidly in recent years.With the promotion of the Internet of Things and the advantages that traditional automatic identification technology does not have,RFID technology is widely used in various fields such as logistics,production,life,medical care,and national defense.The RFID system is mainly composed of three parts:electronic tags,readers and system level applications.The performance of electronic tags has a major impact on the overall performance of RFID systems.Therefore,the research and design of electronic tags have attracted much attention.This paper studies the chip tag antenna,tag MIMO antenna and chipless tag sensor.The main research issues are miniaturization,multienvironment adaptability and sensing characteristics.The main work and results of the paper are as follows:1.So as to realize the normal operation of RFID tags in various environments,a compact UHF RFID tag antenna is proposed for platform tolerant applications.The antenna structure consists of a T-matching network and a folded patch with a U-shaped parasitic in it.Due to the folded structure,the antenna volume is reduced to 26mm×26mm×7mm(0.08?×0.08?×0.02?).In order to enhance the bandwidth,the U-shaped parasitic patch is introduced to generate one more resonant mode.With proximity coupling feed besides the T-matching network,the conjugate matching between the antenna and the chip is realized.The experimental results show that the antenna has the ability to fully cover UHF RFID operating band of 902 MHz to 928 MHz in three typical environments,which can meet the needs of multi-environment applications.2.In order to further improve the communication rate and multipath resistance of RFID system,a UHF RFID MIMO tag antenna is proposed for platform tolerant applications.The antenna structure consists of a foldedpatch,a square patch and a bent loop matching network between two substrates.Due to the folded structure,the antenna volume is reduced to 35mm×35 mm×6 mm(0.1?×0.1?×0.02?).The introduction of the bent loop matching network not only stimulates the outer radiator to generate the required resonant frequency,but also the matching network forms a resonant loop with the chip,which also produces an adjacent resonant frequency to achieving a broadband effect.Orthogonal placement of the feed networks improve isolation between ports.The experimental results show that the antenna has the ability to completely cover UHF RFID operating band of 902 MHz to 928 MHz in three typical environments,which can meet the application needs of multiple environments.And the isolation is greater than30 d B.The envelope correlation coefficient is very small.The antenna can meet MIMO performance requirements.3.In order to realize the design of low-cost RFID sensor,a chipless UHF RFID tag sensor for temperature detection is proposed.The chipless tag sensor consists of a bent dipole and a pair of open resonant rings,using low-cost distilled water as a sensitive material.The planar electromagnetic wave is used to illuminate the tag to obtain the back-scattered signal of the tag,and then the radar scattering surface(RCS) is used to obtain the encoded information.The experimental results show that the sensor has better linearity and sensitivity.Considering cost and performance as well as the gradual improvement of the entire RFID system,the sensor can be used for future target object identification and temperature detection.