A miniature tri-band RFID reader antenna with high gain for portable devices

摘要

This paper presents a miniature monopole reader antenna for tri-band radio frequency identification (RFID) portable devices. The proposed antenna operates at the main RFID frequencies and can alleviate and compensate for the shortcomings of a single-band antenna. An additional rectangular stub couples with the bent monopole antenna, allowing the latter to resonate at the RFID bands at 902-928 MHz, 2.4-2.48 GHz, and 5.725-5.875 GHz. By bending the feedline, the dimensions of the miniature antenna are reduced to 115.5 x 20 x 1.6 mm(3), facilitating its integration into portable devices. The measured bandwidths(return loss < -10 dB) of the proposed antenna are 677, 580, and 250 MHz in the three operating bands, 883-1560 MHz, 2.31-2.89 GHz, and 5.65-5.9 GHz, respectively, with high-gain characteristics. An experimental study of a fabricated prototype of the optimized antenna is performed, and the results verify its good performance.