On Design Of Leaky-wave Antenna For Passive RFID Distributed Coverage Applications

Many applications of IoT(Internet of Things)require that ultra high frequency(UHF)passive radio frequency identification(RFID)technology is able to realize object recognition and environmental information perception in a specified area.When the designated area is a long and narrow,the traditional UHF RFID reader antenna can't complete signal coverage for this area,and using distributed multi-antenna system will increase the complexity of system.Using leaky-wave antenna of transmission line is expected to provide a better solution.In order to address the special requirements for local reading of UHF RFID system and solve the problem of serious shortage of energy radiation in conventional communications,RFID leaky-wave antenna is designed based on coaxial cable and microstrip line in this article.The main research content includes:1.Developed an RFID leaky-wave antenna design based on coaxial cable.Combined with the minimum active power requirements of passive RFID tags,an analysis of the design requirements for UHF passive RFID leaky-wave antenna is given.Then,the slot based on periodic bent structure and triangular structure in outer conductor is optimally designed.The fabricated leaky coaxial cable was processed and tested and it is verified experimentally that using leaky coaxial cable as an RFID reader.2.Developed an RFID leaky-wave antenna design based on coaxial cable For application requirements,a leaky-wave microstrip line was designed on the FR4 dielectric substrate PCB by optimizing the periodic horizontal three-slot eight-character structure on the grounded metal plate,and physical processing and test verification were performed.Then,combined with the engineering application cost control requirements,a leaky-wave microstrip line based on a physical foamed dielectric substrate is designed and it is based on periodic three-slot eight-character structure.Finally,the design of leaky wave microstrip line with debris optimized search technology was explored based on the basis of gap presetting.3.A study of the best working mode for leaky-wave antennas is conducted.The energy decreases in the end of RFID leaky-wave antenna because of strong leakage energy existing along the antenna,and it will lead to a decrease in the reading distance of the end coverage area.It is expected to be improved by controlling the end of the reflection.The RFID leaky-wave antenna is equivalent to the cascade of the leaky-wave cell network and the transmission line network by calculating the scattering matrix of the slot unit.Then,analyze and compare the total leakage power of the antenna and the leakage power of the gap unit when the RFID leaky-wave antenna uses different termination loads.After that,the optimal termination load is given.The results of theoretical analysis and preliminary test show that the RFID reading performance along the line can be adjusted and improved by optimizing the termination load.