A Wideband Circular Polarization Antenna for UHF Tags
Keywords:Axial ratio, circular polarization crossed dipole, RFID, tag antenna
In this paper, a low profile antenna for UHF Radio Frequency Identification (RFID) Tags with wideband circular polarization (CP) is proposed to solve the polarization mismatch in RFID systems. This antenna consists of two orthogonal dipole with unequal slots for realizing circular polarization radiation and a new matching network. For reducing size, a row-shaped tip loading is used. The measurement result of return loss bandwidth is 40 MHz (895-935 MHz) and 3-dB axial ratio bandwidth is 25 MHz (910-935 MHz). The overall size of antenna has been reduced to (0.19 lambda 0 × 0.19 lambda 0 × 0.005 lambda 0 ) at 915 MHz compared to previous works. Besides, other advantages of this design are wideband impedance matching and CP bandwidth.
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