Achieving uniform perpendicular magnetic field distribution for near-field ultra-high frequency radio-frequency identification

摘要

In this study, a new antenna is proposed to achieve uniform perpendicular magnetic field distribution for near-field ultra-high frequency radio-frequency identification. The antenna is based on ‘interdigital-oppositely directed currents (ODCs)’ that is formed by introducing another current between the two oppositely directed currents of ODCs. By adjusting the feeding phase of the newly introduced current, the uniformity of perpendicular magnetic field distribution can be improved. The design procedure of the antenna is presented and the uniform perpendicular magnetic field distribution of the antenna is achieved and verified by experiments. When the transmitting power of the proposed antenna is 1 W, the interrogation area for 100% tag detection is 49 × 16 cm with an observing height of 5 cm for Impinj J41 near-field tags.