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Broadband Design of Planar Circularly Polarized Annular-Ring Antenna for RFID Applications

By Jui-Han Lu and Shin-Chiang Lin
Progress In Electromagnetics Research Letters, Vol. 68, 1-8, 2017


By introducing the Wilkinson divider and dual L-shaped strips as a feeding network, broadband design of planar circularly polarized (CP) annual-ring antenna for ultra-high frequency (UHF) RFID system is proposed and experimentally studied. The proposed broadband CP antenna can provide the impedance bandwidth (RL≥10 dB) of about 246 MHz (25.0% @ 985 MHz) and the 3 dB axial-ratio (AR) bandwidth of about 180 MHz (19.5% @ 925 MHz) to meet the worldwide UHF RFID band (860~960 MHz). Meanwhile, with unidirectional pattern in the XZ- and YZ-planes, the measured peak gain and radiation efficiency are about 7.7 dBic and 70% across the operating band, respectively.


Jui-Han Lu and Shin-Chiang Lin, "Broadband Design of Planar Circularly Polarized Annular-Ring Antenna for RFID Applications," Progress In Electromagnetics Research Letters, Vol. 68, 1-8, 2017.


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