Wave scattering by a transversal defect in a discrete waveguide

Fuente: arXiv
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Autori principali: Medvedeva, Elena, Assier, Raphael, Kisil, Anastasia
Natura: Preprint
Pubblicazione: 2026
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author Medvedeva, Elena
Assier, Raphael
Kisil, Anastasia
author_facet Medvedeva, Elena
Assier, Raphael
Kisil, Anastasia
contents We study wave scattering by a finite transversal strip in a discrete square-lattice waveguide with Dirichlet boundary conditions imposed on the strip and the waveguide walls. The setting is motivated as a discrete analogue of the classical continuous waveguide problem with a screen. The corresponding Wiener--Hopf formulation leads to an equation with a $4 \times 4$ matrix kernel, which reduces to a $2 \times 2$ matrix kernel under some symmetry assumptions. The factorisation prospects of this kernel are discussed, but this route is not followed. Instead, an exact analytical solution is obtained using the pole removal technique. This contrasts with the continuous case, where only approximate solutions are currently available. The reflection and transmission coefficients resulting from an incident duct mode are computed with an accuracy up to $10^{-13}$, showing consistency with theoretical predictions from continuous waveguide theory. In particular, full reflection and zero transmission are recovered as the frequency approaches the cut-off value for the incident mode. Finally, the solution is validated against a numerical computation of the diffraction problem via the Boundary Algebraic Equations method with a tailored lattice Green's function.
format Preprint
id arxiv_https___arxiv_org_abs_2602_10227
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Wave scattering by a transversal defect in a discrete waveguide
Medvedeva, Elena
Assier, Raphael
Kisil, Anastasia
Mathematical Physics
Analysis of PDEs
Complex Variables
We study wave scattering by a finite transversal strip in a discrete square-lattice waveguide with Dirichlet boundary conditions imposed on the strip and the waveguide walls. The setting is motivated as a discrete analogue of the classical continuous waveguide problem with a screen. The corresponding Wiener--Hopf formulation leads to an equation with a $4 \times 4$ matrix kernel, which reduces to a $2 \times 2$ matrix kernel under some symmetry assumptions. The factorisation prospects of this kernel are discussed, but this route is not followed. Instead, an exact analytical solution is obtained using the pole removal technique. This contrasts with the continuous case, where only approximate solutions are currently available. The reflection and transmission coefficients resulting from an incident duct mode are computed with an accuracy up to $10^{-13}$, showing consistency with theoretical predictions from continuous waveguide theory. In particular, full reflection and zero transmission are recovered as the frequency approaches the cut-off value for the incident mode. Finally, the solution is validated against a numerical computation of the diffraction problem via the Boundary Algebraic Equations method with a tailored lattice Green's function.
title Wave scattering by a transversal defect in a discrete waveguide
topic Mathematical Physics
Analysis of PDEs
Complex Variables
url https://arxiv.org/abs/2602.10227