Complementary Planar Inverted-F Antennas (PIFAs) for On-Metal RFID Tag Design

A pair of complementary planar inverted-F antennas (PIFAs), which are tactfully integrated, is employed for designing a compact on-metal tag. Here, two complementing PIFAs that are placed into antipodal style are found to be able of introducing reactive loading effects for reducing the overall size of a UHF RFID tag to 40 × 40 × 3.18 mm
³
. Despite being electrically small, this antenna is able to achieve a long read distance of 10 m (4 W EIRP) when it is tagged on metal. Worth-mentioning is that additional matching network is not required as varying the dimensions of the stubs and narrow slot are already sufficient to tune the antenna impedance for achieving good impedance matching.