Compact Wideband Circularly Polarized Patch Antenna Array Using Metasurface

This letter proposes a compact wideband circularly polarized (CP) antenna array, which is a set of 2 × 2 metasurfacebased CP patch antennas fed by a sequential-phase (SP) network. The single element is composed of a truncated corner square patch sandwiched between the ground plane and the metasurface of a lattice of 4 × 4 periodic metal plates. These metasurface-based antennas are incorporated with the SP network of a sequentially rotated series-parallel feed to achieve wideband operation. The radiation pattern and operational bandwidth in the high-frequency region were improved by reducing the spacing between the driven patches while maintaining the structure and overall size of the metasurface. The final design, with an overall size of 64 × 64 × 2.34 mm ³ (approximately 1.26λ _o × 1.26λ _o × 0.046λ _o at 5.9 GHz), was fabricated and measured. The antenna array has a measured |Sιι| <; -10-dB bandwidth of 4.40-8.00 GHz (58.06%), a 3-dB axial ratio bandwidth of 4.75-7.25 GHz (41.67%), a 3-dB gain bandwidth of 4.8-7.0 GHz (37.3%), and a peak gain of 12.08 dBic at 6.0 GHz. In addition, the antenna array yielded a broadside, left-hand CP radiation with a symmetrical profile, low sidelobe level, and high radiation efficiency.