Acoustic Diffraction of a Plane Wave by Two Coplanar Parallel Perfectly Soft or Rigid Strips

Abstract

The problem of diffraction of a normally incident plane acoustic wave by two parallel and coplanar infinite strips is considered. The assumed boundary conditions on the strips are the vanishing of either the total wave function or its normal derivative. Expressions are obtained for the first few terms of the series for the far-field amplitude and the scattering cross section when the wavelength is much larger than the distance between the outer edges of the strips. The corresponding results for two parallel and coplanar infinite slits in a soft or a rigid screen follow by applying Babinet's principle. This analysis also gives the transmission coefficients for the case of two infinite parallel slits in a thin conducting screen when the electric or magnetic field vectors of the incident plane monochromatic waves are polarized parallel to the edges of the slits.