A Rotation-Controlled Anisotropic Hourglass Metasurface for Multiband Reflective Linear-to-Circular and Cross- Polarization Conversion

Abstract

This paper presents and experimentally validates a multifunctional anisotropic metasurface (MS) that exhibits linear-to-linear (LTL) reflective cross-polarization (RCP) and circular polarization conversion (CPC) responses across multiple frequency ranges. The proposed MS integrates a single-layer design consisting of 45° oriented truncated circular ring and an hourglass-like structure, providing four LTL-RCP conversion bands (2.41 - 2.48, 3.16 - 3.46, 5.80 - 6.59, and 11.64 - 13.75) GHz with polarization conversion ratio (PCR) exceeding 95%, and seven CPC bands (2.33 - 2.38, 2.55 - 2.99, 3.69 - 5.37, 7.13 - 10.92, 13.95 - 14.25, 14.93 - 15.17, and 15.31 - 15.56) GHz with the axial ratio (AR) less than 3 dB, covering the S-, C-, X-, and Ku-bands. By only adjusting the angle of the hourglass structure at 15° within the same structure, LTL-RCP with PCR greater than 95% is realized in the frequency bands from 13.71 to 14.64 GHz, along with ≤ 3 dB of AR is achieved at four additional CPC bands at (2.20 - 2.36, 2.95 - 8.41, 10.84 - 12.30, and 14.84 - 15.06) GHz. The polarization conversion mechanisms are explained through detailed surface-current distributions analysis and full-wave electromagnetic (EM) simulations. Furthermore, the proposed concept is validated through the measurements of the fabricated prototype consisting of 8× 13 -unit cells. The measurement results are in excellent agreement with the simulation predictions. The proposed MS design demonstrates a simple yet effective solution for achieving tunable multi-band polarization manipulation without structural modification, making it suitable for advanced EM communication applications.