Broadband Capacitively Coupled Patch Antenna for RFID Tag Mountable on Metallic Objects

Design of a capacitively coupled meandered patch antenna is presented in this letter. The antenna is fabricated on a very thin substrate with thickness of 0.8 mm and designed for ultrahigh frequency (UHF) band radio frequency identification (RFID) tag mountable on metallic objects. The capacitively coupled feeding technique is used to perform a broadband operation. Bending a long patch into four half-wavelength radiating elements makes the surface currents of all radiating elements in phase, thus achieving an enhanced antenna gain and a good reading range performance. In addition, the proposed antenna mounted on a metallic platform is studied, and no severe degradation in the reading range is observed .