Design of Narrow-Band Filters Based on Dielectric Waveguide Gratings under Plane Wave Excitation

In this paper two types of high-efficiency narrowband filters based on Dielectric Frequency-Selective Surfaces (DFSSs) have been predicted theoretically for plane-wave incidence. Firstly, a DFSS showing total reflection based on the Brewster phenomenon for TM polarization has been designed at a frequency of 10.5 GHz based on a single dielectric grating, showing extremely low-reflectance sidebands adjacent to the resonance peak. Secondly, a band-gap based transmission filter for two-dimensional normal TE incidence has been designed at 11.77 GHz with extremely low sidebands by superimposing the resonance of a waveguide grating on the classical high-reflectance response of an EBG. The selected frequency band is within the first bandgap of a finite length implementation of an EBG lattice formed by alternating homogeneous dielectric layers, in which the central high index layer has been replaced by a DFSS with the same average relative permittivity and thickness. Finally, the oblique incidence and polarization effect on the spectral response of this embedded DFSS has also been studied. In addition, dielectric ohmic losses have been accounted for in both structures.This work was supported by the Ministerio de Economía y Competitividad, Spanish Government, under the coordinated projects TEC2013-47037-C5-4-R and TEC2013-47037-C5-1-R