A dual-band circularly-polarized stacked patch antenna with a small frequency-ratio

Abstract

A novel dual-band circularly-polarized (CP) stacked patch antenna is presented in this paper. The antenna consists of two layers of FR4 substrates separated by an air gap. The dual-band circular polarization is achieved from aperture-coupled elements by a rotated square patch and a circular patch, which are etched on the top and bottom sides of the upper substrate. Computed results show that the -10 dB reflection coefficient bandwidths are 15.4% centered at 2.18 GHz and 14.2% centered at 2.5 GHz, respectively. The 3 dB axial-ratio (AR) bandwidths are 2.75% and 2.6%, which are within the reflection coefficient bandwidths. The frequency ratio of dual bands is 1.148.