A low-cost wideband antenna for radio-frequency identification (RFID) tags for use with metallic foil packages is designed in this communication. An proximity inductively coupled feed structure is employed to perform wideband impedance matching between a slot on a metallic foil package and a small rectangular feeding loop connected to a microchip. The results show a measured half-power bandwidth of 32.2% (799 MHz-1,093 MHz) and a reading distance of over 10 m.