Design of a compact CPW-fed UHF RFID tag antenna for metallic objects

Abstract

A compact CPW-fed UHF RFID tag antenna for metallic objects is proposed. It is less sensitive to the size of metallic objects and has a low profile and a long reading distance. The antenna consists of shorting walls, CPW feed line, a tag IC, and a radiating patch with I-shaped slits. The overall dimensions of the antenna are 55 mm x 26 mm x 2.2 mm. The tag IC has an input impedance of 43 - j800 Omega at 915 MHz. When the antenna is mounted on 200 nun x 200 mm, 400 mm x 400 mm, and 600 mm x 600 mm planar metallic plates, the maximum reading distances are 5.1, 5, and 4.5 m, respectively.