Novel antenna configuration for HF- and UHF-band hybrid card-type RFID tags

This paper presents a novel, effective antenna configuration for HF- and UHF-band hybrid card-type RFID tags. The proposed antenna positively utilizes a coil for operation in the HF band as a ground conductor and acts as a monopole antenna in the UHF band. Capacitive coupling of the coil windings at the vicinity of the UHF feed point helps to reduce the dependency of the radiation efficiency on the coil's dimensions and to obtain higher radiation efficiency in the UHF band. The wideband characteristics and effectiveness of the proposed antenna are demonstrated by electromagnetic simulations and experiments.