Diffraction of a surface wave on a conducting rectangular wedge

Diffraction of a surface wave on a rectangular wedge with impedance facets is studied using the Sommerfeld-Malyuzhinets technique. An analog of Landau's bypass rule in the theory of plasma waves is introduced for the selection of a correct branch of the Sommerfeld integral, and the exact solution is given in terms of the imaginary error function. The formula derived is valid both in the ``near wave'' and ``far wave'' zones (defined here to be located within the wave zone, in the meaning of the theory of radiation). It is shown that a diffracted surface wave is completely scattered into freely propagating electromagnetic waves and neither reflected nor transmitted surface waves are generated in the case of bare metals, which have a positive real part of the surface impedance. The scattered waves propagate predominantly at a grazing angle along the direction of propagation of the incident surface wave and mainly in the upper hemisphere regarding the wedge facet. The profile of radiated intensity is nonmonotonic and does not resemble the surface-wave profile, which exponentially evanesces with the distance from the wedge facet. Comparison with experiments carried out in the terahertz spectral range at the Novosibirsk Free-Electron Laser facility has shown a good agreement of the theory and the experiments.