A Novel Printed Dual-Log-Periodic Array Antenna for UHF Near-Field RFID Applications

A novel printed center-fed dual-log-periodic array antenna is proposed for ultrahigh frequency (UHF) radio frequency identification (RFID) applications. The proposed antenna is composed of two reversed wideband printed log-periodic dipole array antennas. Two closely spaced oppositely directed currents are thus introduced to achieve intensive and uniform magnetic fields in the near-field zone. A prototype antenna is fabricated and measured in practical application environment. The measurement results agree well with the simulations, and demonstrate that the proposed antenna is suitable to be implemented in RFID systems. The operated frequency band of the antenna is 824-953 MHz (14.5%), covering the UHF band in China, the Federal Communications Commission band, and the European Telecommunications Standards Institute band. With the proposed printed dual-log-periodic array antenna, measurement results also show that the RFID system delivers a 100% guaranteed reading rate within 2.0 cm and a maximum reading range of 19.0 cm.