A Bandwidth-Enhanced Circularly Polarized Reflectarray Antenna With Ultralow-Profile Pancharatnam-Berry Metasurface

This letter presents the design and implementation of a bandwidth-enhanced circularly polarized reflectarray antenna (CPRA), which is realized with the novel ultralow-profile subwavelength Pancharatnam-Berry (PB) metasurface based on the triple-mode rectangular ring resonator. The PB metasurface exhibits a third-order quasi-elliptic bandpass frequency response under circularly polarized incidence while maintaining the ultralow profile of 0.04 lambda(0). Stable frequency response of the PB meta-atom can be observed with the oblique incidence up to 30 degrees in a wide frequency range. To validate the CPRA design method, a Ku-band offset-fed CPRA prototype with a left-hand circularly polarized (LHCP) feed antenna has been designed, fabricated, and measured. The measured CPRA performance aligns well with simulations, demonstrating that the measured 1 dB gain bandwidth and 3 dB axial-ratio (AR) bandwidth are 8.8% and 10.1%, respectively. Meanwhile, the maximum antenna gain of the CPRA reaches up to 25.0 dBic at 15 GHz with the corresponding aperture efficiency of 51.3%.