Research And Design Of Chipless RFID Sensor Tag With Anti-clutter Performance

Nowadays,with the rapid development of the Internet of Things,radio frequency identification technology has been widely used in logistics tracking,identification,national defense and military fields.At present,due to the high cost of chip RFID sensor tags,the design of low-cost chipless RFID sensor tags has become a research hotspot.In this paper,the anticlutter performance of chipless RFID sensor tag is studied and designed.The structure design,polarization conversion characteristics and sensing performance of the sensor tag are analyzed.The main work and outcomes are as follows:1)Aiming at the application of sensing the dielectric constant of materials in natural environment,this paper proposes a design of chipless RFID sensor tag with good anti-clutter performance.The tag resonator structure has polarization conversion characteristics and contains a metal ground plate.And the reader uses orthogonal methods to send and receive signals,which can effectively filter out the interference clutter generated by the environment.The tag coding is realized by 4 groups of asymmetric Z-shaped metal strip resonators with compact structure and small mutual coupling.The metal patch of the sensing resonator has a stepped gap,where the dielectric constant of the measured material affects the resonance frequency of the sensing resonator.The dielectric constant sensing is realized by measuring the resonance frequency.The simulation model was built to analyze the design,and the results from both aspects of coding and sensing verified the feasibility of the design.2)In order to improve the anti-clutter performance of tag in the measured environment,a design of anti-clutter chipless RFID tag based on miniaturized ELC resonator is proposed.The whole structure is composed of metal ground plate and three different sizes of centrosymmetric ELC resonators.The metal ground plate can improve the anti-metal performance of the tag,the central symmetric ELC resonator makes the tag compact and has polarization conversion characteristics,and is insensitive to polarization angle and incident angle,so the tag has better anti-clutter performance.The coded ELC resonator changes the length of metal strip through user-defined solder joint to affect the structure equivalent inductance,and uses frequency shift coding to effectively improve the coding capacity.The sensor ELC resonator changes the dielectric constant of the material to affect the structure equivalent capacitance,so that the corresponding resonant frequency of the label is frequency shifted.A tag simulation model is built,and the resonant frequency,Q value and polarization conversion characteristics of the structure are analyzed.It is found that the sensor has high discrimination,sensitivity and anti-clutter performance.Then the stability and reliability of the design in practical application are verified by actual measurement.3)In order to improve the polarization conversion characteristics of the metal ring structure,a combined metal ring anti-clutter chipless RFID angle sensor tag is designed by using the coupling characteristics between the rings.In this design,several metal rings with different radii are combined and arranged at a certain angle,so that the polarization conversion characteristics of the tag structure become obvious,the anti-clutter performance is improved,and the angle sensing function is provided.Using the above method,two kinds of tag structures are designed,which are the central symmetric metal four ring tag and the asymmetric metal five ring tag.Both designs use metal grounding plates,which can effectively improve the metal resistance of the tag.The sensing principle is mainly because the component of different radius combined metal ring in the direction of incident wave affects the polarization conversion characteristics of the tag structure,which makes the amplitude of the corresponding resonant frequency change.Therefore,when the tag rotates at a certain angle,the corresponding angle can be determined according to the amplitude difference under different resonant frequencies.The simulation model of the tag is built,and the two sensors are verified in theory.Then through the actual measurement,it is found that the corresponding resonance peak value of the sensor is obvious,and the anti-clutter ability is good.However,due to uncontrollable factors such as platform environment and operation error,the accuracy of the angle sensor needs to be further improved.