A Hybrid 2-D–3-D Miniaturized Multiorder Wide Bandpass FSS

In this letter, a hybrid multi-order wide bandpass FSS with high selectivity and low insertion loss is achieved by combining the 2D FSS structure and 3D vertical structure. The 3D periodic vertical printed circuit board pieces (PVPCB) are used as the dielectric layer in the unit cell to achieve a proper band flatness without introducing great insertion loss. The multi-order response of the proposed FSS is achieved using a series of 3D PVPCB instead of stacking the 2D FSS layers. The proposed FSS unit cell is constructed by combining the full-wave and equivalent circuit simulations, since the physical structures have a good one-to-one correspondence with the circuit elements. The module design method is used to accelerate the design procedure, and the simulation result proves the effectiveness of this design method. Finally, the prototype is fabricated and measured to prove the effectiveness of the proposed FSS. The measured relative bandwidth and rectangle coefficient achieve 130.4% and 0.76, respectively. The measured maximum insertion loss over whole passband is 0.7 dB. Because of its strong capability of out-of-band rejection, the proposed FSS structure is a good candidate to enhance high frequency electromagnetic pulse protection of wideband radar systems.