The Physical Reality of Zenneck's Surface Wave

N 1907 1 Zenneck showed that a plane interface between two semiinfinite media could support, or guide, an electromagnetic wave which is exponentially attenuated in the direction of propagation along the interface and vertically upwards and downwards from the interface. Zenneck did not show that an antenna could generate such a wave but, because this "surface wave" seemed to be a plausible explanation of the propagation of radio waves to great distances, it was commonly accepted as one of the components of the radiation from an antenna.