Films with angular and spectral selectivity of the optical transmittance were produced by reactive magnetron sputtering with oblique incidence of the deposition species towards a substrate. These data could be reconciled with multiparameter fits to a model based on the Maxwell Garnett effective medium theory applied to a three-component structure with inclined columns, surrounded by voids, comprised of elongated Al particles in an Al2O3 matrix. (C) 1995 American Institute of Physics.