Slots in metallic label as RFID tag antenna

In this paper, we present a low cost slot antenna for the integration of an RFID tag into a metallic label used in a hardware supply chain. The metallic label is covered with a plastic layer on one side on which information is printed and the RFID functionality is a complement to this printed information. The prerequisite for altering such a label is that it should still be possible to run it through a conventional label printer and thus that there should be a sufficiently large area remaining unaltered in order for the printed information to be held. While previous work by Siden et al. (2006) has reported how this can be solved with the aid of a specially designed dipole and a highly flexible foam spacer, this work presents a solution that needs no extra structure and thus is cheaper and more convenient to fabricate. By cutting slots on a 76 times 76 mm metallic label, we achieve a reliable remote identification of this label at 869 MHz. The slot antenna has an almost omni-directional radiation pattern and the RFID tag constituted by this slot antenna and an RFID chip has a maximum read range of almost 5 m.