Design and Analysis of Wide Band Linear to Circular Polarization Converter for Sub-Thz Applications

In this paper, the design and analysis of a transmission-type linear-to-circular polarization converter (LCPC) operating in the sub-terahertz frequency range is presented. The proposed structure features a simple and compact geometry. The proposed LCPC consists of four layers of fused silica with a horizontally oriented gold strip printed on the top layer of substrate. The design achieves a wide 3-dB axial ratio bandwidth (ARBW) of 52.6%(154−164GHz) under normal incidence and maintains polarization conversion performance for oblique incidence angles up to 10°. The equivalent circuit model (ECM) of the proposed LCPC validates its working as the results of ECM and full wave solver are in close agreement to each other. Furthermore, the converter exhibits an extinction ratio exceeding 15 dB within the 160−255GHz frequency band and achieves a transmission efficiency greater than 75 % across 154−254GHZ frequency range. The working of proposed LCPC is also validated through an ECM. These results demonstrate the suitability of the proposed LCPC for high-performance terahertz applications requiring efficient and broadband circular polarization.