Passive HF RFID Repeater for Communicating With Tags in Metal Housings

This letter presents, for the first time, a custom-built high frequency (HF) radio frequency identification (RFID) system that enables the communication with an RFID transponder (tag), which is attached to an object located in an enclosedmetal housing. Proof-of-concept measurements of the custom-built HF RFID system show a good system performance and a favorable extension of the read range in the metal environment by 19% in comparison to the read range of the free space system. These results are realized by a novel passive repeater structure, which is included in the system (i.e., reader-repeater-tag). The passive repeater consists of an arrangement of two booster antennas and ferrite material. Next to simulation and measurement results, this letter provides an equivalent circuit model of the reader-repeater-tag system for system design.