A Realistic Coaxial Feed for Cascaded Cylindrical Metasurfaces

In this letter, a realistic coaxial feed is integrated into the design of cascaded cylindrical metasurfaces. This is in contrast to the fictitious current source that is often reported in literature. The
$S$
-matrix of the coaxial feed is obtained by way of the mode-matching technique, which is subsequently combined with the
$S$
-matrix of the cascaded cylindrical metasurfaces to account for the interaction between the feed and metasurfaces. The integration of a realistic feed into the design process enables practical cylindrical-metasurface-based devices.