Study of broadband near-field antenna for ultra-highfrequency radio frequency identification applications

A novel antenna for applications in an ultra-high-frequency (UHF) radio frequency identification (RFID) reader system is proposed and investigated. The antenna achieves a gain of lower than -10-dBi in all directions with strong magnetic field distribution over the entire UHF RFID band of 830-950-MHz as well as good performance in detecting tags when applied in UHF RFID systems. The antenna configuration is described and the principle of operation is explained. To investigate the effects of each parameter on the antenna performance, a comprehensive parametric study is carried out and the results are presented in detail and discussed. To prove the concept, a prototype is developed and fabricated. The measurement results demonstrate that the antenna can achieve a broad bandwidth and low gain, and produce a strong magnetic field with relatively concentrated field distribution in the near-field region of the antenna. Hence, this work is very promising for UHF near-field RFID reader applications.