毫米波二阶分形频率选择表面寄生谐振的抑制

二阶分形频率选择表面具有良好的双频特性, 是实现准光学选频网络小型化的理想选择. 但是由于其自相似迭代结构的复杂性, 导致其长期受到寄生谐振的影响, 为了提高二阶分形结构在工程应用中的可靠性, 本文建立了二阶方环分形周期单元的等效电路并分析了寄生谐振产生时的场分布情况, 研究了寄生谐振的形成机理; 进而通过单元间去耦合操作, 并引入基于离散粒子群算法的多参数优化过程, 克服了这一问题. 仿真和实验结果表明: 在保证双频工作特性、对于入射角和极化稳定的前提下, 通过去耦合和粒子群算法实现的频率选择表面实测对寄生谐振的抑制可达13dB, 且避免了新的寄生谐振的产生. 关于寄生谐振抑制的研究, 为增强二阶分形阵列结构的可靠性提供了新的思路. 关键词： 二阶分形 频率选择表面 寄生谐振 离散粒子群算法

Restrain the spurious resonance of second-order fractal frequency selective surface in MMW band

Based on analyzing the equivalent circuit and electric field distribution of second-order square fractal frequency selective surface (FSS), the mechanism of its spurious resonance is discussed. To achieve a millimeter wave (MMW) spatial filter which exhibits high out-band suppression(≥13dB) and insensitive to the variation of oblique incident angles for both TE and TM polarized waves, a hybrid methodology of decoupling operation in conjunction with discrete particle swarm optimization (DPSO) procedure is proposed. The FSS array without spurious resonance and its evolutionary process by DPSO are described. It is also demonstrated that the measured results and DPSO-operated frequency characteristics are in excellent agreement.
Keywords： second order fractal frequency selective surface spurious resonance discrete particle swarm optimization