Metamaterial inspired Ultra-Thin Polarization-Separated UWB FSS to mitigate Ku and K-Band electromagnetic interference

Abstract

A novel design approach is proposed for a sub-wavelength ultrathin (0.00973λ₀) hexagonal snowflake-like fractal configured and diagonally coupled resonator-based frequency selective surface (DCR-FSS), where λ₀ is the lower stop band wavelength in free space. The proposed DCR-FSS demonstrates excellent polarization separation characteristics, revealing a single transmission zero (TZ) in TE mode and dual TZs in TM mode, while maintaining |S₂₁ |≤ −10 dB from 14.6 to 26 GHz, covering the Ku and K band spectral range. Metallic gap adjustment between triangular slotted regions in corner-coupled metallic patches is utilized to finely adjust the TZ and bandwidth. Equivalent circuit models (ECM) in TE and TM modes are introduced to validate the proposed design strategy. Notably, the stop band exhibits dual-negative negative index metamaterial (DNG-NIM) (Re[ε_r] < 0, Re[μ_r] < 0) characteristics around the corresponding TZs for both the TE and TM polarization. Furthermore, significant angular stability up to 30° angles of incidence is achieved with a 2.1 % and 2.5 % frequency deviation in TE and TM modes respectively. Eventually, the proposed design is experimentally validated for both planar and conformal surfaces, yielding results consistent with simulations and measurements.