Imperfect strip gratings near Wood anomalies

A new approach to analysis of periodic gratings composed of imperfect strip conductors is presented. Separation of the spectral and spatial singularities in Green´s function has led to regularisation of the problem in the vicinities of Wood´s anomalies. The developed technique gives the well-conditioned, uniformly convergent and numerically stable solutions of the scattering problems. The obtained solutions provide a physical insight in the mechanisms of loss in strip gratings.