Low-profile microstrip antenna with bandwidth enhancement for radio frequency identification applications

Abstract

Two low-profile microstrip antennas, which can be mounted on metallic objects for radio frequency identification applications, are proposed. By using a single-layer FR4 as the substrate, the thickness of the antennas is only 1.6 mm (about 1% dielectric wavelength at 900 MHz). In order to broaden the bandwidth, slots are added on the surface of the patch to excite two different modes. Compared to conventional microstrip antennas, the impedance bandwidth (voltage standing wave ratio < 3) of the design can reach 100 MHz, and the 3-dB gain bandwidth is about 50 MHz, which can satisfy most applications for UHF radio frequency identification systems. The size of the compact design is only 84 mm×26 mm. Prototypes were fabricated and measured. The read range of the designed antennas can reach 4 m when mounted on metallic plates. Copyright © Taylor & Francis Group, LLC.