A major challenge in the implementation of optical elements in the millimeter band is to minimize the radiation loss caused by reflection. The widely used method is based on the realization of an Anti-Reflection Coating (ARC), which exploits the behaviour of interference of the radiation generated by the deposition of one or more layers of polymeric material on the optical element, so as to obtain a unique surface having a refractive index conveniently selected. The major limitations that affect the ARC reside in the complexity of manufacturing, with consequent increase of costs, and possible bonding process issues after several cooling cycles; an essential feature to achieve measurements at these wavelengths. Here we report about an alternative and innovative technique based on the realization of mechanical Anti-Reflection Structures (ARS), possibly a simpler and more economic manufacture, based on the mechanical processing of the surface of a dielectric material. The antireflective behaviour is linked to the geometrical texture of the surface. The simulations of these ARS provide us with a detailed analysis of the optical properties for different geometrical realizations. The results will be compared with those of the ARC and further experimentally validated. Particular attention is put on to the analysis of the possible presence of spurious polarization effects, because this type of technology could find employment in the realization of cold optical elements for telescopes devoted to Cosmic Microwave Background (CMB) observations.