Balanced RFID Tag Antenna Mountable on Metallic Plates

A novel balanced tag antenna for radio frequency identification (RFID) system is presented. The radiating elements of two planar inverted-F antennas (PIFAs) are inductively coupled by the feed loop with out of phase. The balanced structure provides smaller degradation of performances when an RFID tag is mounted on the various sizes of metal plates. The HFSS simulator is employed to analyze the proposed antenna in the design process and to compare with measured results.