Broadband Design Using Matrix Analysis Of Frequency Selective Surface Inserted At The Center Of Dielectric Plate In Millimeter-Wave Band

Thicknesses of window glasses, radomes, plastic cases of wireless systems are comparable with the wavelength in the millimeter-wave band. The reflections from the dielectric plate surfaces are canceled out of phase when the thickness is identical to a half of the wavelength. The reflection loss is minimum at the resonant frequency. However, they are not canceled at any other frequencies except integer multiple of a half wavelength. Therefore, the return loss is a serious problem in the millimeter-wave band. We propose to insert a frequency selective surface (FSS) at the center of the dielectric plate, which satisfies the phase condition to cancel three reflections from two dielectric surfaces and the FSS. A wide bandwidth for low return loss was obtained by generating three resonances, which satisfy the amplitude condition to cancel the three reflections. The matrix analysis is applied in the calculation of the scattering matrices (S-matrix) of the three reflections in this paper.