Diffraction of surface wave on conducting rectangular wedge

TL;DR

This paper presents an exact analytical solution for the diffraction of surface waves on a conducting rectangular wedge, revealing how incident waves scatter into free-space waves with specific angular and intensity profiles, validated by terahertz experiments.

Contribution

It introduces a novel application of the Sommerfeld-Malyuzhinets technique with an analog of Landau's bypass rule for surface wave diffraction analysis.

Findings

Diffraction results in complete scattering into free-space waves for bare metals.

Radiated waves propagate mainly at grazing angles and in the upper hemisphere.

Theoretical predictions agree well with terahertz experimental data.

Abstract

Diffraction of a surface wave on a rectangular wedge with impedance faces is studied using the Sommerfeld-Malyuzhinets technique. An analog of Landau's bypass rule in the theory of plasma waves is introduced for selection of a correct branch of the Sommerfeld integral, and the exact solution is given in terms of imaginary error function. The formula derived is valid both in the near-field and far-wave zones. 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 case of bare metals which have positive real part of 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 face. The profile of radiated intensity is nonmonotonic and does not resemble the surface wave profile which exponentially evanesces with the distance from the wedge face. Comparison with experiments carried out in the terahertz spectral range at Novosibirsk free electron laser has shown a good agreement of the theory and the experiments.