Circularly Polarized Meander Line Cross Dipole Antenna for UHF RFID Applications

In this paper, a new cross dipole Radio Frequency Identification circularly polarized tag antenna operating in the ultra-high frequency region is introduced. Circular polarization is achieved using two unequal orthogonal dipoles. The arms of the orthogonal dipoles are meandered and loaded with capacitive tips for size miniaturization. A meandered T-match network is used to obtain impedance matching with Impinj Monza-4 tag chip used for the design. The measured 10-dB return loss bandwidth and the 3 dB axial ratio bandwidth are 17 MHz (908-923 MHz) and 6 MHz (912-918 MHz) respectively. A significant improvement in the read range of the proposed antenna compared to a linearly polarized antenna of similar gain and reflection coefficient, from 10.9 m to 15.66 m, has been achieved due to reduced polarization mismatch between the tag and the reader antennas.