2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/159217We investigate Fano-type anomalous transmission of energy of plane waves across lossless slab scatterers with periodic structure in the presence of non-robust guided modes. Our approach is based on rigorous analytic perturbation of the scattering problem near a guided mode and applies to very general structures, continuous and discrete.Mathematical Physics78M35text