Offset-symmetric dual-ring resonators for dual-resonance huygens-type transmissive frequency selective surface

This paper proposes a novel design scheme for a Huygens-type transmissive frequency selective surface (FSS). To improve the efficiency of electromagnetic wavefront control on a single-layer dielectric substrate, the scheme employs a double-ring resonator unit with offset-symmetric characteristics. This unit excites the in-phase superposition of equivalent electric and magnetic dipoles through structural asymmetry, thereby satisfying the Huygens Condition. In the Ka and V bands, it exhibits excellent transmission characteristics, with a power transmittance exceeding 81.7% (peaking at 95.69%). Simulation and experimental results show that the proposed FSS forms dual resonant points at 31.33 GHz and 41.01 GHz, achieving high transmission efficiency on a single-layer dielectric substrate. It should be noted that the proposed FSS exhibits two transmission peaks within a single contiguous passband (30.3–42.6 GHz), rather than two isolated bands separated by a rejection band. Therefore, the term “dual-resonance” is used throughout this paper to accurately describe the spectral response. The proposed design provides a low-profile, easily integrable FSS implementation scheme for high-frequency communication systems.