Simultaneously Dual-Polarization Convertible Sub- THz Reconfigurable Intelligent Surface Enabled by Through-Quartz VIAs

In this paper, simultaneously dual-polarization convertible sub- THz reconfigurable intelligent surface (RIS) enabled by through-quartz VIAs is proposed. The proposed RIS has two functionalities: beam steering and polarization conversion. Liquid crystal (LC) is placed under the metal pattern and works as a tunable substrate, which makes it possible to steer the beam. The metal pattern, placed above the LC layer, converts the TE polarization to the TM polarization and vice versa. To avoid polarization conversion performance degradation, the through- VIA on a quartz substrate is introduced. To drill the holes in the quartz substrate, a sanding technique with μm-sized particles is used and copper is filled in the holes to form VIAs. Then the conventional display manufacturing process is utilized to fabricate the proposed RIS. The proposed RIS unit cell has 130° of phase tuning range with 45 μm cell gap. The experimental results show that the proposed RIS satisfies both intended functions.