Novel CPW-fed slot antenna for UHF RFID metal tag applications

Abstract

A novel planar CPW-fed passive tag antenna that may be mounted on a metallic object is presented to meet UHF radio frequency identification (RFID) applications. It comes with a slot radiator and an inverted-C shaped coupling structure, which is fabricated on a 0.4mm-thick FR4 substrate to be attached on a 3mm-thick polypropylene (PP) substrate. No additional matching circuit is required with our design, so a compact tag size of 93(L)×20(W)×3.4(H)mm³ can be obtained. With a proper operating bandwidth from 915 to 929MHz, the proposed tag can achieve maximum reading ranges of 7.4m and 4.7m when used with and without a metallic plate for 4W EIRP.