Millimeter-wave broadband dual-circularly polarized array antenna loaded with metasurface

This paper presents a millimeter-wave broadband dual circularly polarized (DCP) linear array antenna loaded with a linear to circular polarization converting metasurface. The feeding element employs a circular patch into which a symmetric cross-shaped slot is etched, dividing the patch into four electrically isolated, equal-area sectors. The original electric-field distribution is reconfigured by the proposed geometry, yielding simultaneous horizontal and vertical linear polarization. The linearly polarized electric field is converted to a dual circularly polarized electric field by the metasurface. Compactness and simplicity offer excellent scalability. A 1 × 4 array is fabricated and measured to verify the validity of the design. The measured results show good agreement with the simulation. Measured results show an impedance bandwidth (IBW) of 24.2% (26.5-33.8 GHz), an axial ratio (AR) bandwidth of 21.6% (27.2-33.8 GHz), and a gain of 13.4 dBic at the center frequency.