Snell´s law applied to finite surfaces

Snell´s law of reflection applies to a plane wave incident on an infinite surface. For finite surfaces the size of the surface, the angle of incidence, and the polarization of the incident wave all contribute to deviations from Snell´s law. An eigenfunction expansion for the scattering pattern of a perfectly conducting strip and experimental bistatic scattering measurements of rectangular plates are used to verify the deviations. Physical optics calculations also predict these deviations and are used to provide a physical explanation for the deviations