On Stabilization of the Bandwidth of a Dichroic Surface by Use of Dielectric Slabs

Abstract

ABSTRACT Dichroic surfaces, also called Frequency Selectric Surfaces (FSS), are typically made of periodic surfaces of either dipole or slot like elements. In either case, a significant change of bandwidth is generally experienced as a function of Incidence angle and polarization. In this paper it is shown that using dielectric slabs with the surface can greatly reduce this bandwidth variation. The dielectric slabs must have the proper dielectric constant (usually less than 2) and proper thickness (approximately a quarter wavelength, measured In the slab). An example of such a dichroic surface is given. This surface is reflective in the range 27.5 to 30.0 GHz and transparent in the range 17.7 to 20.2 GHz. The surface operates for arbitrary polarization and incidence angles from 0° (normal) to 75°. It is comprised of two dipole like periodic structures sandwiched between three dielectric slabs.