Broadband CPW-fed RFID Antenna at 2.45/5.80 GHz

A kind of half-ring folded-slot antennas with CPW-fed structure is presented. Two antennas which operate at 2.45 GHz and 5.80 GHz band are designed and fabricated respectively. The 2.45 GHz one with the size of 30 x 36 mm has bandwidth of 17.6 % (VSWR les 2:1) and gain of 1.76~2.21 dBi; the 5.80 GHz one has bandwidth of 26 % (VSWR les 2:1) and gain of 2.9~3.3 dBi, while the size is just 16 x 15 mm. By simulation and test, the radiation pattern is almost omnidirectional in the H-plane. This kind of antennas is suitable for radio frequency identification (RFID) application at 2.45/5.80 GHz.