Computation of waveguide scattering matrix near thresholds

Abstract

A waveguide occupies infinite strip with one or several narrows on a two-dimensional (2D) plane and is governed by the Helmholtz equation with Dirichlet boundary condition. On the waveguide continuous spectrum, which coincides with a half-axis, a scattering matrix is defined. At each point of the continuous spectrum this matrix has finite size, which changes at thresholds. The thresholds form a sequence of positive numbers increasing to infinity. Approximate calculation of the scattering matrix in a threshold vicinity requires special treatment. We discuss and compare two methods of numerical approximation to the scattering matrix near a threshold.

Keywords:

• Helmholtz equation
• scattering matrix
• threshold
• augmented wave space

AMS Subject Classifications:

• 65M99
• 65N99
• 65Z99

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the SPbGU [project number 11.38.666.2013].