Metal mount RFID tag antenna excited by integrated loop/IC module

A simple topology is described for radio frequency identification (RFID) tags mountable on metal surfaces. The tag is built around a commercial UHF RFID module combining an IC and a coupling loop. The module is placed in the neighbourhood of a slot which is used both to couple the energy from the module to the patch-like antenna and to miniaturise the tag. A read range of almost 4 m is obtained in the 865-868 MHz band with a 1.6 mm low-cost FR4 substrate.