Active Transmission-Type Metasurface for Linear-to-Circular Polarization Conversion at a Certain Frequency Band

An active transmission-type metasurface is presented, which is based on double metallic patches incorporated with active components of PIN diodes. It can be numerically obtained that the left circularly polarized(LCP) wave is transmitted at 4.3-4.48 GHz with a transmission coefficient of 25-46% under the OFF state of PIN diodes when the the structure is impinged by a $x$ polarization. In addition, the ability of converting a y- polarized incident wave to a right circularly polarized(RCP) wave at the same frequency band is unambiguously exhibited with a transmission coefficient of 29.2-43.4% by actively controlling switchable PIN diodes. The proposed metasurface could be an active and dynamic approach to manipulate linear to circular(LTC) polarization conversion at a fixed frequency band.