A highly efficient and broadband metasurface for linear-to-linear and linear-to-circular polarization conversion in reflection mode

This research paper introduces a new design of metasurface for polarization conversion applications, functioning as both a cross (half-wave plate) and circular (quarter wave plate) polarizer in reflection mode. Comprising unit cells on one side and a metal layer on the other, with a Roger 5880 substrate, the metasurface demonstrates its ability to reflect an incident $x$- or $y$-polarized wave as a $y$- or $x$-polarized wave across multiple frequency bands: 9.72–10.00 GHz, 17.65–41.87 GHz, 45.67–45.80 GHz, and 49.66–49.84 GHz. The design achieves a noteworthy 24.82 GHz bandwidth with a 98.72 % fractional bandwidth for linear-to-linear conversion, demonstrating efficiency exceeding 90 %. Simultaneously, the metasurface converts the incident wave into a right-hand circularly polarized (RHCP) wave at frequencies ranging from 9.38 to 9.61 GHz, 45.9–46.1 GHz, and 49.96–50 GHz. It transforms the wave into a left-hand circularly polarized (LHCP) wave within the frequency band from 10.19 to 10.61 GHz, 15.60–16.82 GHz, and 45.45–45.6 GHz. The design also exhibits angular stability up to 45 degrees. Experimental validation using the fabricated prototype confirms the findings, showing good agreement with numerical results. This metasurface comes in handy for future communication, radar application, and health applications. This metasurface is highly suitable for future communication systems, radar applications, and healthcare technologies.