Characteristics of passive UHF RFID tags on metal slabs

In this paper, the passive UHF RFID tag is characterized on a metal slab for varying distances. The bent dipole tag designed by UPM Raflatac Corporation and the Squiggle tag designed by Alien Corporation is tested for electromagnetic strength of the reply signal. These tags are also simulated in FEKO 5.3 designed by EMSS to depict their performances on the metal slab for varying distances, and is compared theoretically to the loaded meander tag designed by Intermec Corporation. Each tag is also evaluated independently for wire and surface currents to give insights into their operation around metals. Theory and simulations are used to predict three stages (destructive, constructive, and expansionary) in tag responses for varying distances from the metal slabs. Fundamental testing is also conducted to validate the simulations presented here.