A Tri-band, small size radio frequency identification tag antenna with u-shaped slots

A new multiband, small size antenna for passive radio frequency identification (RFID) tags is presented. Placement of three U-shaped slots can create three independent resonances within the RFID range: 0.953, 2.45, and 5.8 GHz, whereas in each resonance, particular inductive input impedance will be achieved by a simple technique to be conjugately matched with the capacitive impedance of the chosen electronic chip. The proposed simple structural antenna is flexibly tunable to be matched with other chips in RFID frequencies. It is shown that the matching and forward patterns of tag antenna in each band are desirable, simultaneously. Details of the proposed antenna design and measured results are presented.