This paper presents an ultra-thin, ultra-wideband linear-to-circular (LTC) polarization converter based on the crossed-dipole-shaped metasurface. The unit cell of the crossed-dipole-shaped metasurface is made up of two identical T-shaped dipole arms, which are orthogonal to each other and are connected with a diagonal microstrip line. The LTC polarization converter is placed on the top side of an ultra-thin single-substrate layer with a profile size of 0.035λo , where λo is a free space wavelength at the center frequency of the axial ratio bandwidth (20.89 GHz). The proposed design shows nearly equal transmission amplitude and stable phase difference of nearly 90° of the two orthogonal components of transmitted waves in a wide frequency range. The right-hand circularly polarized (RHCP) component of the transmitted wave is much larger than the left-hand circularly polarized, and thus, the transmitted wave is RHCP. Numerical and experimental results showed that the polarizer could realize an ultra-wideband LTC polarization conversion at both x- and y-polarized incidences in the frequency range from 11.66 to 30.12 GHz, which is a fractional bandwidth of 88.4%, and it can maintain a stable polarization conversion performance under large-range incidence angles. In addition, a high total transmittance of the electromagnetic wave was obtained.
This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by Korean Government Ministry of Science and ICT (MSIT) under Grant NRF-2022R1F1A1065324; in part by the Institute of Information and Communications Technology Planning and Evaluation (IITP) grant funded by Korean Government (MSIT), Development of 3D-NET Core Technology for High-Mobility Vehicular Service, under Grant 2022-0-00704-001; and in part by the Institute of Information and Communications Technology Planning and Evaluation (IITP) grant funded by Korean Government (MSIT) under Grant RS-2024-00396992.This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2022R1F1A1065324); in part by the Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korea government (MSIT) (No. 2019-0-00098, Advanced and Integrated Software Development for Electromagnetic Analysis); and in part by the Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korea government (MSIT) (No. 2022-0-00704, Development of 3D-NET Core Technology for High-Mobility Vehicular Service).
