Research On RFID Chipless Tags Coding And Sensing Technology

With the rise of concepts such as "Internet of Things+" and "Feeling China" in recent years,the "Internet of things" technology has developed rapidly.Radio frequency identification technology,which is one of the key technologies of the Internet of Things,has also ushered in a new stage of development.It has been widely used in industrial automation,transportation,logistics,new retail and other fields.At the same time,the high production and use costs of existing RFID tags limit the possibility of their large-scale application.Therefore,a chipless tag technology that can reduce the cost of tags and replace existing optical barcode tracking products has emerged and developed rapidly.Based on the above situation,applying the relevant theories of electromagnetic fields,antennas,and testing,this paper studies the principle of encoding and sensing of RFID chipless tags,and designs a chipless tag based on hybrid encoding and two chipless sensing tags.The work includes:First of all,this dissertation describes the work and sensing principle of the chipless RPID system,and analyzes the important role of electromagnetic,antenna and other theory in the design and detection of chipless tags.From the differences between the chipless RFID system and the traditional chip RFID system,the challenges and advantages of the chipless tag technology are introduced;Using the small-electric antenna equivalent model to illustrate the design classification of the current perceptual chipless tags;The method of calculating the scattering cross section and antenna gain of the chipless tag is obtained by radar scattering principle and antenna technology.The influence of the surface current or electric field distribution of the chipless tags conductor on its structural design and detection was analyzed using different signal deployment methods.Secondly,this dissertation proposes a hybrid coding chipless tag based on frequency coding technique and amplitude shift keying.By analyzing different types of chipless tags coding principles and comparing the performance of different types of coding structures,a 3CP chipless tag using 3 modified C-shaped structures as radio frequency encoded particles was designed.The overall structure of the tag is made of copper conductor and carbon nano conductive ink.According to simulation and test results,the 3CP chipless tag can encode 23.9 bits of data in an area of 40 mm×30 mm,and the code density reaches 1.99 bit/cm2.In addition,by simply increasing the number of C-shaped REP,the amount of data encoded by chipless tags can be greatly increased.When using 4 REP,the chipless tag designed in this paper can encode more than 37 bits.Finally,this dissertation designs two sensing chipless tags that use different principles:resistance sensing type C-R chipless tags and angle sensing type FSRR-A chipless tag.The C-R chipless tags utilize the relationship between the loaded lumped resistance value and the X-axis direction scattered electric field intensity Exto realize the detection of the lumped resistance R.Through the test and simulation results,the average value of the detection error of the C-R chipless tags to the resistance is less than 5%,and the maximum value of the resistance value detection is less than 1Ω,except in some cases.The FSRR-A chipless tags also use the relationship between the X-axis directional scattered field intensity Ex and the acute angle between the incident wave polarization direction and the SRR opening direction to calculate 0.According to the simulation results,the detection error for the included angle 0 is less than 3.5%,and the included angle difference is basically less than 2°.In the FSRR-A chipless tags design process,folding size reduction technology has been used to reduce the plane size of the SSRR structure more than 30%.