On the scaling of inclusions size in metal-dielectric windows at normal incidence

A three-quarters wavelength thick metal-dielectric electromagnetic (EM) window is investigated. The window is centrally loaded by a periodic array of sub-resonant conducting inclusions, and has a wider frequency bandwidth than the standard half-wavelength thick window. Using spherical inclusions, we show that for every grid-constant of the periodic array there is a radius of the inclusions that minimizes the reflection from the window. We discuss the scaling law that governs these optimized structures.