Free and on metal modified T-shaped tag antenna for UHF-RFID applications

In this paper, a new modified T-shaped antenna for RFID-UHF tag application is presented. To achieve a good conjugate matching between the tag chip and the antenna, the technique of adding four half-circle shaped patches at the both ends of each T monopoles was applied. The measured maximum read range in free space is 7.5. By adding foam substrate of thickness 3 mm between the tag antenna and the metallic plate the read range remains constant. Details of the proposed tag antenna design, as well as simulated and measured results are presented and discussed in this paper.