Miniaturised UHF RFID Tag Antenna Design for AC Current Sensing

This paper proposes a new tag antenna design for the dual RFID tag system for ac current sensing in smart metering systems. The proposed tag antenna design is based on an electrical dipole and the meander line technique is used to reduce the size of the antenna without affecting the reading range. The tag antenna occupies a small area of 46 mm x 33 mm. The antenna port impedance was conjugately matched with the input impedance of the Magnus S2 chip at 868 MHz, and the resultant reflection coefficient is less than -10 dB and the realised gain is 0.36 dB. The measured result shows that the miniaturised tag antenna can transmit current readings over a read range of 6 m using the 868 MHz UHF band.