Abstract: Defected Ground Structure（DGS）, as a class of Frequency Selective Surfaces（FSS）, can be widely applied in the electromagnetic field in order to increase Signal Noise Ratio（SNR）. A new DGS FSS with the novel structure units is proposed in this paper, which can be used to design the Band Elimination Filter（BEF）. CN-FDTD（Crank-Nicolson FDTD）, as an unconditionally stable FDTD, is still stabile and effective when the time step is much greater than the Courant-Friedrich-Levy（CFL）limit. The precise numerical analysis for this structure is completed through CN-FDTD. The influences of many parameters, such as the parameter l, on the BEF characteristic are studied in detail. Good filter characteristic can be obtained through altering some appropriate parameters. The helpful conclusion given in the paper can be served as a powerful tool to analyze and design the BEF. It is shown that the numerical error of CN-FDTD increases with the augmentation of the time step.

Key words: defected ground structure, frequency selective surfaces, Crank-Nicolson Finite-Different Time-Domain（CN-FDTD）, band elimination filter

摘要： 缺陷接地结构（DGS）作为频率选择表面（FSS）的一类，在电磁领域应用广泛。提出了一种新颖结构单元的DGS频率选择表面，可以用来实现带阻滤波器（BEF）。Crank-Nicolson FDTD（CN-FDTD）是一种无条件稳定的FDTD，在时间步长取值远大于Courant-Friedrich-Levy（CFL）稳定性条件时，CN-FDTD仍然稳定而且可靠。利用CN-FDTD对该结构进行了精确的数值计算，研究了参数[l]、参数[g]和周期单元数[n]对这种带阻滤波器滤波特性的影响。随着参数[l]的增大、参数[g]的减小和周期单元数[n]的增大，带阻滤波器的滤波特性越好。这些有益的结论能为这种新颖DGS带阻滤波器的分析和设计提供有力的指导。讨论了CN-FDTD的误差项，随着时间步长的增大，其误差也会显著增大。

关键词: 缺陷接地结构, 频率选择表面, Crank-Nicolson时域有限差分法（CN-FDTD）, 带阻滤波器