A surface wave launcher for launching electromagnetic surface waves, the launcher comprising: a waveguide comprising a planar conductive layer; a feed structure comprising a first conductor, the first conductor coupled to the waveguide at a coupling; wherein the waveguide is arranged to be positioned adjacent to a surface suitable for guiding electromagnetic surface waves; and wherein the planar conductive layer comprises one or more slots each having a pair of longitudinal edge, the one or more slots extending through the conductive layer and arranged such that an axis radially extending from the coupling intersects each pair of longitudinal edges of the one or more slots.