Low-Profile Flexible UHF RFID Tag Design for Wristbands Applications

In this study, a low-profile ultrahigh frequency (UHF) radio-frequency identification (RFID) tag antenna designed for wristbands in healthcare applications is proposed. The radiator is based on the open-slot cavity technique that is composed of a slotted patch (double-T slots) loaded onto a flexible open cavity. The proposed slotted design can easily allow the tag's input impedance to be tuned to the complex impedance of typical UHF RFID chips. The proposed tag antenna has a size of 86 mm x 25 mm x 1.6 mm (0.26 lambda(0) x 0.07 lambda(0) x 0.004 lambda(0)) at 915 MHz, and it can yield a maximum reading range of 8 m (stand alone in free-space condition), 6.6 m (when placed on the human wrist in free-space condition), and up to 3 m (when placed on the human wrist in a crowded condition).