A Wideband Circularly-Polarized Transmitarray Using Parallel Dielectric Plate-Based Unit Cells with Negative Anisotropy Slop

A solution to enhance the axial ratio (AR) bandwidth of a circularly-polarized (CP) planar transmitarray using 3D printed parallel dielectric plate unit cells is presented here. Unlike the conventional anisotropic structure with positive anisotropic slope property, a structure with negative anisotropic slope property is proposed, which exhibits a wider polarization conversion bandwidth. By further incorporating element rotation and geometrical variation, a 6-state phase adjustment scheme is adopted to design a 540-elements circular-aperture CP transmitarray. Promising results are demonstrated experimentally, showing an aperture efficiency of 41%, a wide 1-dB gain bandwidth of 25% and overlapped 3-dB gain and AR bandwidth of 42.4%. With these substantial advancements, the proposed approach opens exciting avenues for designing wideband polarizers and discrete lenses based on 3D printed anisotropic structures. © 2024 IEEE.