Design And Application Of Near Field Scanning RFID Reader Antenna

With the development of radio frequency technology,antennas with uniform near-field forming for RFID reader have attracted much attention.However,the power consumption of RFID system is often very high for the case of large reading area.In this paper,a near-field scannable array antenna is proposed to orderly realize local-area label induction within the reading area,thus effectively saving the power consumption of the RFID system.Specifically,the reconfigurable feeding network for reader array antenna is designed by using PIN diode,and the power consumption of the array antenna under identical amplitude and phase feeding and scanning conditions is compared;at the same time,the comparison of power saving per unit reading area between linear polarized antenna array and circular polarized antenna array under near-field scanning and the same amplitude and phase conditions is made.The contents of this paper include several aspects:1.In order to accurately model the reconfigurable feeder network,a PIN diode parameter measurement fixture and corresponding TRL calibration kit are designed,and the corresponding circuit parameters are extracted through the equivalent circuit modeling of PIN diode.Full-wave HFSS simulation,ADS simulation and physical test of the switching network based on PIN transistor design are carried out.The results are consistent,which verifies the correctness of the circuit parameters of PIN transistor.2.A circularly polarized dual-layer patch near-field scanning RFID reader array antenna controlled by reconfigurable feeding network and a circularly polarized RFID reader array antenna controlled by an equal-amplitude and in-phase feeding network are designed.The power consumption of the two antennas under different cell numbers is compared.The results of simulation and measurement show that the near-field scanning array antenna can save more power than the same-amplitude in-phase array antenna when the scanning area increases or the number of antenna elements increases.3.Near-field scanning line-polarized and circular-polarized RFID reader array antennas are designed,as well as linear-polarized and circular-polarized RFID reader array antennas fed with the same amplitude and phase.The power consumption of the four antennas in the number of 2,4 and 6 units is compared respectively.The simulation and measurement results show that the near-field scanning circular polarization array antenna consumes more power than the near-field scanning linear polarization antenna in the unit card reading area,but the near-field scanning circular polarization array antenna saves more power than the near-field scanning linear polarization antenna in the unit card reading area.