Compact Symmetric Quad-Arm Meander-Line RFID Tag Antenna for Metallic Surface Applications

A miniaturized UHF RFID tag antenna designed for use with the Ucode 8/8m IC chip—characterized by an input impedance of 15 – j217 Ω at 915 MHz—is introduced. To ensure optimal power transfer, the antenna geometry was meticulously refined to achieve conjugate impedance matching with the chip. The final total structure, measuring 50 × 50 × 0.4 mm³, delivers a power transmission coefficient of up to 95% and supports a read range exceeding 8.0 meters when operating under an effective isotropic radiated power (EIRP) of 4.0 W. Performance testing was carried out with the tag affixed to a 250 × 250 mm² metal surface, demonstrating reliable functionality in metallic environments. The antenna is tuned to operate within the FCC-designated UHF RFID frequency band (902–928 MHz), suitable for deployment in North America and Vietnam. Experimental measurements closely matched full-wave simulation results, validating both the impedance-matching strategy and the overall design efficiency.