Ultra-Miniaturized Low-Profile Angularly-Stable Frequency Selective Surface Design

In this study, an ultra-miniaturized low-profile angularly-stable frequency selective surface (FSS) based on 2.5-dimension convoluted interwoven element is designed. The dimension of FSS element is 0.014λ
₀
× 0.014λ
₀
, where the λ
₀
represents the free-space wavelength of resonance frequency. The thickness is only 0.0015λ
₀
. When the FSS is illuminated by electromagnetic wave, the frequency selective properties perform stable under different incident angles up to 85° for both TE and TM polarization. For better understanding, the operation mechanism, the design procedure, distribution of surface current, and equivalent circuit are presented. A prototype of proposed FSS is fabricated, the measurement results prove the validity of simulated ones. To further improve the performance, using the same design procedure, the size and thickness of designed FSS have been reduced to 0.0053λ
₀
× 0.0053λ
₀
and 0.00061λ
₀
, respectively. Since the resonance frequency of proposed FSS is adjustable at any desired frequency, an ultra-miniaturized low-profile angularly-stable FSS for GSM 900 band has been designed. The designed FSS can be applied in GSM shielding effectively.