A low‐profile and miniaturized frequency selective surface (FSS) with dual‐polarized bandpass characteristics is proposed in this article. The FSS is a second‐order structure with two layers separated by an air spacer, achieving two transmission poles (TPs) and two transmission zeros (TZs) at both sides of the TPs. Using the miniaturized structure, the physical dimension of the element is reduced to 0.09λ × 0.09λ, where λ is the free‐space wavelength at the center frequency. Thus, the structure exhibits stable performance with respect to different incident angles. The overall thickness is 0.053λ, which is much thinner than alternative second‐order FSSs using the traditional cascading technique. This feature makes it a candidate to be applied in low frequency bands with long wavelengths. In addition, the operating principle of the proposed structure is analyzed by using the equivalent circuit method (ECM) and the surface current distribution is also given. Finally, a prototype is fabricated and measured to validate the simulated results.

中文翻译：

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具有低轮廓和小型化特性的准椭圆带通频率选择表面

本文提出了一种具有双极化带通特性的低轮廓和小型化的频率选择性表面（FSS）。FSS是一种二级结构，其两层之间由空气垫片隔开，从而在TP的两侧实现了两个传输极（TP）和两个传输零点（TZ）。使用小型化的结构，所述元件的物理尺寸减小到0.09 λ  ×0.09 λ，其中λ是在中心频率的自由空间波长。因此，该结构对于不同的入射角表现出稳定的性能。总厚度为0.053 λ，它比使用传统级联技术的替代二阶FSS薄得多。此功能使其成为长波长低频段应用的候选者。此外，通过等效电路法（ECM）分析了所提出结构的工作原理，并给出了表面电流分布。最后，制造并测量原型以验证仿真结果。