COMPACT METAL-MOUNTABLE UHF RFID TAG ANTENNA WITH TWO LARGE C-SHAPED SLOTS FOR ON-THE-FLY TUNING

A compact folded-patch UHF RFID tag antenna (30mm × 30mm × 3mm or 0.0912λ × 0.0912λ × 0.009λ) is proposed for metallic surface applications. Two large C-shaped slots, which can be easily tuned by adjusting their lengths, are incorporated into the folded-patch for providing tuning mechanisms that can be employed in the production line for tuning the tag resonant frequency on the fly. The slots are tactfully embedded into the patch structure so that they occupy no footprint. The slots are large enough so that their lengths can be easily adjusted by employing a penknife and some copper tapes. This provides an impromptu tuning mechanism so that the tag resonant frequency can be easily corrected in the production line. With reference to the effective isotropic radiated power of 4W, the proposed tag antenna can be read from 10 m on metal. The read range is found to be able to go beyond 5.5 m when the tag is placed on a dielectric with permittivity ranging from 1 to 12.