Design and Experimental Validation of Linear to Circular Polarization Converter for Point to Point THz Communication

This letter presents a compact, low-profile single-substrate transmissive linear-to-circular polarization (LCP) converter designed and experimentally validated for point-to-point THz communication bands. The proposed LCP converter consists of an H-shaped gold metallic pattern deposited on both sides of a 100 µm-thick fused silica substrate. The LCP converter operates within the 0.225– 0.307 THz frequency band, achieving a simulated 3-dB axial ratio bandwidth of 30.8% in simulation. Owing to its wide axial ratio bandwidth, the proposed design is a promising candidate for point-to-point THz communication applications. The performance of the proposed converter is verified through surface current distribution, which explains the occurrence of Hyugen’s response and equivalent circuit model. The proposed converter exhibits a measured 3-dB axial-ratio bandwidth of 27.8% in the frequency band 0.229–0.303 THz. The simple geometry and single-substrate implementation, with a thin profile and wide 3-dB axial ratio bandwidth, make the proposed design suitable for practical deployment scenarios.