Dual-band circularly polarized hexagonal-slot antenna

Abstract

A dual-band, circularly polarized, hexagonal-shaped slot antenna is proposed and studied using microstrip feed with L-shaped stub. The antenna consists of a hexagonal-shaped slot with a microstrip feed and L-shaped stub. An impedance transformer is used to improve the impedance matching of the slot antenna. The slot and feeding structure are fabricated on a low cost FR4 substrate. The measured results of the antenna prototype are 15.7% (3.2-3.75 GHz)\15.5% (4.42-5.1 GHz) for 3-dB axial ratio bandwidths and 8.6% (3.41-3.70 GHz)\15.5% (4.47-5.20 GHz) for VSWR<;2 impedance bandwidths, respectively, for the 3.5 GHz and 4.5 GHz operating frequency bands. The measured gain is around 4.3 dBic for 3.5 GHz band and 3.0 dBic for 4.5 GHz band at the boresight.