Planar, Lightweight, Circularly Polarized Crossed Dipole Antenna for Handheld UHF RFID Reader

Abstract

ABSTRACTA planar, lightweight, crossed dipole antenna with circularly polarized (CP) radiation is introduced for application in a radiofrequency identification handheld reader at ultrahigh frequency bands. The dipoles cross through a 90° phase‐delay line of a vacant‐quarter printed ring that enables broadband characteristic in terms of impedance matching and 3‐dB axial ratio (AR) bandwidths. Four printed inductors are symmetrically inserted into the dipole arms whose ends are barbed to achieve a compact size. A sample antenna with a size of 60 × 60 × 0.508 mm and weight of 3.6 g is designed, fabricated, and measured. The proposed antenna yields an impedance bandwidth of 851–941 MHz for |S11| < −10 dB and a 3‐dB AR bandwidth of 902–921 MHz. At 910 MHz, the antenna radiates bidirectional CP waves with a gain of 1.4 dBic and an AR of 1.1 dB. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1874–1878, 2013