高选择性三通带三维频率选择表面的研究

提出一种双极化、高选择性的三通带三维频率选择表面(3D FSS).该3D FSS单元结构由四层方形介质筒组成,提供一个平行板波导(PPW)路径和三个方同轴波导(SCW)路径.由于每个SCW路径中两个相同短SCW谐振单元的电磁耦合,由SCW路径端面方形槽提供的原有单一谐振模式分裂为奇模和偶模谐振模式,产生了两个传输极点,由此形成了一个二阶通带,因此三个SCW路径能实现三个二阶通带.此外,由于不同路径之间的电磁波相位反相叠加产生了多个传输零点,提高了该FSS的频率选择性.为了解释该3D FSS的工作原理,研究了传输零极点处的电场矢量分布.仿真结果显示,所提出的3D FSS在横向电场(TE)和横向磁场(TM)极化模式下以0°到60°角度入射时具有稳定的频率响应,同时该3D FSS具有小通带比和较小的单元尺寸.

Investigation of highly-selective tri-passband three-dimensional frequency selective surface

A dual-polarized, highly-selective tri-passband three-dimensional frequency selective surface (3D FSS)is proposed. The unit cell of the proposed 3D FSS consists of four layers of square dielectric tubes, which provides one parallel plate waveguide (PPW) path and three square coaxial waveguide (SCW) paths. Owing to the electromagnetic coupling between two same short SCW resonant elements in each SCW path, original single resonant mode provided by the square slot on the end face of SCW path will split into even- and odd-resonant modes, introducing two transmission poles, and then forming a second-order passband. Thus, three SCW paths can realize three second-order passbands. In addition, the electromagnetic waves in different paths are combined out-of-phase,which can generate multiple transmission zeros and improve the frequency selectivity of this FSS.In order to explain the operating principle of the proposed 3D FSS, the distributions of electric-field vector at the frequencies of the transmission zeros/poles are investigated. The simulated results show that the proposed 3D FSS exhibits stable frequency responses to variations of incident angle from 0° to 60° under both transverse electric (TE) and transverse magnetic (TM) polarizations. Meanwhile,this 3D FSS has small band ratios and relatively compact unit cell size.