Metal Mountable UHF RFID Tag Design Requiring Screw Fixing

This paper describes the design of an ultra-high frequency (UHF) radio frequency identification (RFID) tag for metallic surfaces which can be fixed with metal screws. A shorted annular ring microstrip patch antenna operating in TM01mode is considered to create an “electromagnetic dead zone” at the patch center (current null), making possible the presence of a central screw without disrupting the antenna’ s radiation performance. An accurate analysis of geometrical and material parameters’ effects to the impedance matching and gain behaviors is performed to show the flexibility of the proposed design for implementation in accordance with heterogeneous application’s requirements. Experimental results show an antenna conical pattern with a read range of 4.3 m when the tag is implemented on a low cost 2 mm thick FR4 substrate of diameter 50 mm, and no substantial performance variation when a M6 screw is used to fix it on the metallic surface, which demonstrates the discussed idea.