Experimental characterization of microwave self-complimentary metasurfaces for linear-to-circular polarization transform

Metasurfaces are artificial electromagnetic boundaries usually implemented as two-dimensional periodic arrays of engineered inclusions with sub-wavelength periodicity, which may serve as useful tools to control characteristics of electromagnetic fields. Recently the authors have proposed employing a class of frequency selective metasurfaces with self-complimentary patterns to construct optically thin linear-to-circular (LP-to-CP) polarization transformers. In contrast to previously known designs, such metasurfaces provide the phase shift of nearly 90° between two orthogonal transmitted linear polarizations at any frequency. This constancy of the phase shift makes the design procedure considerably simpler. In this contribution, we focus on experimental realization and characterization of self-complimentary LP-to-CP polarization transformers in the microwave range. By comparison of two particular metasurfaces (the narrowband and the broadband ones), we illustrate their reachable properties and practical design limitations.