  A linear-to-circular polarization converter with half transmission and half
reflection using a single-layered metamaterial is theoretically and numerically
demonstrated. The unit cell of the metamaterial consists of two coupled
split-ring resonators with identical dimensions. A theoretical analysis based
on an electrical circuit model of the coupled split-ring resonators indicates
that the linear-to-circular polarization converter is achieved when the
magnetic coupling between the split-ring resonators is set to a certain
strength. A finite-difference time-domain simulation reveals that the
single-layered metamaterial behaves as the linear-to-circular polarization
converter and that the polarization converter has the combined characteristics
of a half mirror and a quarter-wave plate.
