Alumina ceramic slot antenna for UHF RFID tag embedded in vehicles

Abstract

To address the metallic interference problem in vehicular RFID (radio‐frequency identification) applications, this letter proposes a novel alumina ceramic slot tag antenna (ACSTA). The proposed antenna consists of a grounded thin alumina ceramic substrate and a slotted top layer rectangular patch, and the all four sides of the substrate are shorting walls. The slot can be equivalent to a horizontal magnetic current flow, so an excellent radiation performance is achieved according to the electromagnetic image theory. Meanwhile, due to the existence of the ground plane, the influences of metallic objects behind the ground to the tag antenna impedance can be maximally reduced. Combined with a commercial chip, this ACSTA is fabricated and measured, and the thickness of the novel tag is only 1mm. The tag antenna offers a half power coefficient bandwidth of 6.9% (0.87–0.93 GHz) with a stable gain about 3.6 dBi, and a similar half power coefficient bandwidth of 6.9% (0.89–0.95 GHz) with a gain about 4.8 dBi when it is attached to an 100 × 100 mm2 metallic plate, respectively. Moreover, the experimental results show that the maximum read range is about 27 or 30 m without or with a same attached 100 × 100 mm2 metallic plate, respectively. Simulation and measurement results show that the operating frequency band of the ACSTA covers US legal UHF RFID (902—928 MHz) band, and so it is a quite suitable candidate for vehicular RFID applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1150–1154, 2016