Double-Layer Matching Structures (Correspondence)

In the millimeter wavelength region, as in other regions, the design of matching layers for dielectric surfaces is limited by the lack of suitable dielectric materials. Artificial dielectric layers, formed by periodic perturbations of the boundary surface, are not practical because of the small physical dimensions required. The following approach uses two layers of materials whose relative dielectric constants are given. The thicknesses of the layers are chosen to eliminate reflections at the desired center frequency. A broad-band match is obtained because the layers can be made less than an eighth wavelength in thickness.