Tri-Beam UHF-RFID Tag Antenna for Indoor Asset Tracking

Abstract

This paper proposes a multi-beam UHF RFID tag antenna for indoor localization and tracking. Three dipole structures are placed on a dielectric substrate with hexagonal shape. To distinguish the angle of detection, an equilateral triangle reflector is centrally situated with all sides in parallel with the printed dipoles on the same substrate. This allows distinction between the beams corresponding to each dipole. The antenna is simulated using CST MW studio. NXP UCODE G2iL passive RFID chips are used to conjugately match with the input impedance of the dipole antennas. The radiation patterns show separation between the main lobe of the beams apart by θ = 120° with a radiation efficiency of 29%. A back-reflector representing the top area of a moving robot is also added to elevate the beams to enhance tag antenna's detection footprint. With the back reflector, the main-lobe orientation is elevated to θ= 35° with a 25.21 % radiation efficiency.