  This paper aims at studying the angular scattering properties of
bianisotropic metasurfaces and at clarifying the different roles played by
tangential and normal polarization densities. Different types of metasurfaces
are considered for this study and are classified according to their
symmetrical/asymmetrical and reciprocal/nonreciprocal angular scattering
behavior. Finally, the paper presents the relationships between the symmetrical
angular scattering properties of reciprocal metasurfaces and the structural
symmetries of their scattering particles. This may prove to be practically
useful for the implementation of metasurfaces with complex angular scattering
characteristics.
