Miniaturized UHF near-field RFID reader antenna inspired by meta-resonator

In this paper, a metamaterial-based radio frequency identification (RFID) near-field antenna is proposed with good reading performance for ultra-high frequency (UHF) application. The antenna is composed of a small dipole and two dual-layer pin-connected split ring resonators (SRRs), which are equivalent to magnetic dipoles. Strong and uniform magnetic field distribution is observed with in-phase current flowing on the loops. The measured antenna frequency bandwidth is 4.52%, ranging from 887 MHz to 928 MHz. A large interrogation zone is realized which is verified by a near-field experimental system even if the size of the antenna is less than 1/8 λ. 100 % reading rate is achieved within a reading volume of 210 mm × 180 mm × 100 mm.