Electrically small loop antenna for UHF band RFID tag

UHF band RFID tag antenna which has a similar radiation pattern of the electrically small loop antenna is presented. The structure of the proposed tag antenna is a small circular dipole array on the xy-plane, and the antenna is fed by inductively coupled loop to flow a uniform amplitude and in phased current along its circumference. Since its radiation pattern has an omnidirectional pattern in the xy-plane, the proposed tag antenna can reduce the interference among adjacent tag antennas arranged parallel to xy-plane.