On-body semi-electrically-small tag antenna for ultra high frequency radio-frequency identification platform-tolerant applications

摘要

In this study, the authors proposed the impedance-flexible on-body semi-electrically-small tag antenna for the European ultra-high frequency radio-frequency identification (UHF RFID) frequency band. The radiator is based on differentially-fed coupled shorted-patches and vertical folding techniques, using a loop excitation. The proposed excitation methods enable the input impedance to be tuned to the complex impedance of typical UHF RFID chips as well as to 50 Ω impedance. In addition, the virtual electric short applied inside the structure simplifies the topology and manufacture. The antenna dimensions are 40 × 50 × 3 mm (0.12 × 0.14 × 0.01 ) and represent the electrical size = 0.58 at 866 MHz. The total efficiency measured in open space exceeds 60%. In case that the antenna is situated on a human phantom, it accounts for 50%. Accordingly, the antenna provides the read range of 5.6 m (in open space) and 5.1 m (when located on human chest).