  Although a rigorous theoretical ground on metasurfaces has been established
in the recent years on the basis of the equivalence principle, the majority of
metasurfaces for converting a propagating wave into a surface wave are
developed in accordance with the so-called generalized Snell's law being a
simple heuristic rule for performing wave transformations. Recently, for the
first time, Tcvetkova et al. [Phys. Rev. B 97, 115447 (2018)] have rigorously
studied this problem by means of a reflecting anisotropic metasurface, which
is, unfortunately, difficult to realize, and no experimental results are
available. In this paper, we propose an alternative practical design of a
metasurface-based converter by separating the incident plane wave and the
surface wave in different half-spaces. It allows one to preserve the
polarization of the incident wave and substitute the anisotropic metasurface by
an omega-bianisotropic one. The problem is approached from two sides: By
directly solving the corresponding boundary problem and by considering the
``time-reversed'' scenario when a surface wave is converted into a nonuniform
plane wave. We develop a practical three-layer metasurface based on a
conventional printed circuit board technology to mimic the omega-bianisotropic
response. The metasurface incorporates metallic walls to avoid coupling between
adjacent unit cells and accelerate the design procedure. The design is
validated with full-wave three-dimensional numerical simulations and
demonstrates high conversion efficiency.
