Design of a Bandwidth-Improved, Directive Antenna for a Pavement RFID Tag

This paper presents a novel, directive RFID tag antenna for pavement embedded application. The tag antenna is made of a two-element, closely spaced Yagi antenna; a multiply folded driver and a bowtie strip director. At 908 MHz, the antenna has an input impedance of 36 + j131 Ω, which matches well with the conjugate of Higgs-3 chip impedance of 20 - j135 Ω. The maximum directivity of 5.7 dBi is achieved at 908 MHz. The designed antenna covers the entire US required UHF RFID bandwidth ranging from 902 MHz to 928 MHz.