Conformal Miniaturized Angular Stable Triband Frequency Selective Surface for EMI Shielding

This article presents single-layer conformal high angle stable miniaturized triband bandstop frequency selective surface (FSS) for microwave shielding. This new FSS is supported on an ultrathin dielectric substrate and has stable response with change in polarization and incidence angle. Via-less convoluted geometry is adopted in the unit cell design to increase spatial efficiency with a unit cell size of 0.091 lambda$_L$, where lambda$_L$ is the wavelength at lowest resonance. The proposed FSS exhibits three transmission zeros at 4, 6.95, 11.3 GHz with stopband bandwidth (BW) founds application for shielding the C/X band frequencies for satellite communication. A prototype of the proposed FSS is fabricated. The filter response is measured on normal and on curved surfaces. Simulated and measured transmission coefficients confirm the operating principle of the FSS. Unit cell periodicity of the triband FSS is further reduced by using two layers based 2.5-D geometry. The modified unit cell has a periodicity of 0.038 lambda$_L$ and exhibits stopband BWs center at 0.8, 1.4, and 2.36 GHz.