Passive UHF-RFID tag based on electrically small square-shaped split ring resonator (SRR) antenna

An electrically small passive UHF-RFID tag based on a square-shaped split ring resonator antenna is presented. An analytical formulation of the radiation properties and the chip impedance matching is provided. A tag prototype of size 31 mm × 31 mm (λ₀/11 × λ₀/11) is designed and fabricated. The simulated and measured results are in good agreement with the theoretical analysis and the measured read range reaches 12 m. The tag also features a significant mitigation of blind spots, providing a minimum measured read range of 5.5 m.