A near-field antenna for ultra-high frequency radio frequency identification (RFID) reader with a multi-ring structure and uniform magnetic field was designed. The antenna was circular in shape and consisted of 8 fan-shaped radiating patches distributed in rotation. Through coupling between fan-shaped radiating patches and loading parasitic arc-shaped patches, the surface current of the antenna showed the same rotation direction, which could generate a relatively uniform magnetic field and a multi-polarized electric field in the identification area. The antenna had a diameter of 130 mm and was printed on a flame retardant 4 (FR-4) dielectric substrate with a thickness of 1.6 mm. The measured results show that the bandwidth of the reflection coefficient |S11|<-10 dB is 904~932 MHz. A relatively uniform magnetic field can be generated within a circular area with a diameter of 130 mm above the antenna. At a power output of 30 dBm, the farthest reading distance for the 100% identification rate of the magnetic coupled ring tag J41 is 16 cm when the Impinj E710 reader is used for tag testing. The proposed antenna can generate a multi-polarized electric field that exhibits similar readability for tags placed in different directions
