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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 λL, where λL 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 λL and exhibits stopband BWs center at 0.8, 1.4, and 2.36 GHz. [ABSTRACT FROM AUTHOR]

This article presents a new method of enhancing the capacitance of a single-layer conformal frequency selective surface (FSS) for multifunctional operation. The unit cell of the FSS consists of gridded square loop-loaded modified Jerusalem cross (JC) element. End capacitance of the conventional JC FSS is enhanced by placing parallel diagonal strips, resulting in a pair of reflection zeros near the sidebands. The modified geometry provides high selective stopband filtering that reflects the signal at 20.16 GHz with S21 < −10 dB stopband bandwidth of 20.52%. The FSS shows stable stopband reflection up to a high incidence angle of 85°. The stability in the filter response is also achieved at various conformal angles. The proposed FSS is optimized for dual-band near-perfect absorption. At two resonances 12.76 and 22.54 GHz, the absorption are 99.88% and 99.1%, respectively. Prototypes of the stopband FSS and the dual-band absorber are fabricated to verify the feasibility of the proposed concept. The measured filter and absorber responses are found consistent with the simulated results. As a conformal multifunctional structure, the proposed FSS has the merits of electromagnetic interference shielding and radar cross section reduction in stealth application. [ABSTRACT FROM AUTHOR]