Design of Wideband Metasurface-Based Linear to Circular Polarizers

We provide a new theoretical method to compute the required sheet admittance of the metasurfaces (MSs) used to implement a wideband linear-to-circular polarization converter (LP-to-CP), which consists of three cascaded MSs, separated by dielectric slabs. Each MS is modeled as a shunt load while the slabs are represented by transmission lines. The presented method is based on reactance Foster theorem and image technique of filter design. This method is applied to a three-sheet PCB based LP-to-CP optimized for normal incidence at Ka-band for SATCOM applications. The resulted LP-to-CP yields ideal axial ratio with perfect matching. The method is validated by full wave simulation where the derived sheet admittances of the ideal LP-to-CP are realized by lumped LC tanks found using pole-zero placement technique, then verified by full wave simulations. It is shown that this realization give satisfactory results in terms of axial ratio and transmission coefficients of the transmitted field.