  Hyperbolic metasurfaces have gained significant attention due to their
extraordinary electromagnetic properties to control propagating plane waves,
but the excitation and propagation of the surface plasmon-polaritons at
hyperbolic metasurfaces, called hyperbolic plasmons, have been experimentally
observed just recently. However, the advantages of the hyperbolic plasmons,
such as hybrid TE-TM polarization discussed below, are not yet fully revealed
and analyzed. In this paper we focus on the numerical and experimental
characterization of surface waves in the frequency range from 2 to 8 GHz
supported by a hyperbolic metasurface composed of anisotropic metallic
Jerusalem crosses printed on a thin dielectric substrate. We show different
shapes of equal frequency contours, which correspond to a plethora of
excitation and propagation regimes of surface waves. The principal novelty of
this work consists in the experimental demonstration of the surface waves with
a hybrid, i.e. mixed TE-TM, polarization. Surface waves with a hybrid
polarization are the promising tool in a number of applications and phenomena
including polarization converters, plasmonic sensors, plasmon steering over a
surface, optical forces, spin-orbit photonics, and highlight the impact for the
on-chip and planar networks.
