F. Bentosela, M. Tater Scattering by a slab: an exact calculation (851K, LaTeX 2e with 5 PS Figures) ABSTRACT. The model consists of an infinite number of point interactions distributed periodically on a finite number of parallel planes. Exact formulas for the transmission coefficients are given. Numerical behavior is presented, first in the case the incident plane wave has a wave vector perpendicular to the planes and then for some tilted directions. For some values of the interaction parameter the reflection coefficient is close to one for a relatively large set of incident wavelengths.