Nonreciprocal Metasurfaces with Selective Polarization using Circularly and Linearly Polarized Patch Radiators

The manuscript presents the designs of two nonreciprocal / directional metasurfaces (MSFs) operating in the 3.5 GHz frequency band. The first one presents a Circular Polarization to Circular Polarization (CP-to-CP) MSF where the MSF cell consists of a circularly polarized patch antenna with truncated corners in each side of the multi-layer surface with the use of transistors along the signal path. A similar method with two transistors and a via that connects the radiators in each side, is also used for the second case, where a circular polarization to linear polarization (CP-to-LP) MSF is implemented with the converted propagated linearly polarized wave to be selectively chosen between two orthogonal polarizations. The two transistors along the transmission lines deny the propagation along the opposite direction and they enhance the propagated wave in the preferred direction.