Microstrip Dipole UHF-RFID Tag Antenna for Metal Object Tagging

Two designs of microstrip dipole ultra-high-frequency (UHF) RFID tag antenna which can be used for metal object tagging are presented. The antennas, which have a very simple structure without any shorting pin and shorting plate, are composed of meander and ladder feed lines, rectangular loop, capacitive tip-loading and T-match structure. In addition, a full ground plane has been inserted in both tag antenna designs in order to ensure that the tags can work properly when attached on metal object. The tags are designed to operate in the frequency range of 919 - 923 MHz, which is the frequency range of Malaysia. The simulation has been carried out using CST Simulation software. The simulated and measured results of both tag antenna designs in terms of impedance matching, reflection coefficient and tag reading range has been compared and analyzed. The measured reading range obtained when the Design 1 and Design 2 tag attached on metal object is 2.0 m and 2.2 m respectively.