Scattering Characteristics Analysis of Diffraction Grating Using Hybrid Trefftz Finite Element Method

A formulation based on hybrid variational principle for plane wave scattering problems of infinite periodic gratings is presented. Employing Trefftz finite elements to estimate functionals of infinite half spaces above and below gratings, and applying conventional finite elements to the grating regions, we can estimate the functionals of the whole analyzing region. Therefore computed results converge monotonically with increasing number of conventional finite elements and number of space harmonics for Trefftz elements. Scattering characteristics of lossless dielectric gratings, lossless and lossy metallic gratings are computed and the validiy and usefulness of this method are confirmed