Dual-Band 3-D Frequency Selective Surface With Multiple Transmission Zeros

A dual-band three-dimensional (3-D) frequency selective surface (FSS) is presented for dual-polarized applications in this letter. The proposed 3-D FSS is based on simple square coaxial waveguides and employs via holes, H-shaped slots, and centered gaps in a single unit cell for introducing more resonances and couplings, leading to multiple transmission zeros/poles. As a result, two passbands can be obtained, and each passband contains two transmission poles. Meanwhile, a sharp roll-off rejection of two passbands is achieved by the existence of multiple transmission zeros. The measurement results show a stable response under different incident angles up to 40° for both TE and TM polarizations, with a small unit cell size of 0.13λ0 × 0.13λ0 × 0.17λ0.