Abstract: A novel tunable rectangular rings DGS is proposed，which can be used to design microwave filter.The precise transmission coefficient of tunable rectangular rings DGS is obtained through FDTD analysis.The influences of lattice dimensions on the characteristic of frequency are studied.The results of the FDTD simulation show good agreements with the results of measurement in the references.The influences of straight microstrip line on the characteristic of frequency are also studied.A method about controlling the cut-off frequency by altering the dimensions of straight microstrip line or the lattice dimensions is presented and discussed.The relation given in this paper will provide powerful tool for the analysis and design of microwave filter using tunable rectangular rings DGS.

Key words: defected ground structure, microwave filter, Finite Difference Time Domain（FDTD）, cut-off frequency

摘要： 提出了一种新颖的可调谐矩形环缺陷接地结构（DGS），可以用来实现微波滤波器。对矩形环DGS进行了精确的时域有限差分法（FDTD）数值分析，研究了其几何尺寸变化对阻带特性的影响。将FDTD计算结果与有关文献的测量结果进行了比较，一致性很好，从而验证了FDTD程序的有效性和计算的正确性。在微带平面添加短截线，研究了短截线的尺寸变化对阻带特性的影响。通过研究可知，可以通过改变矩形环DGS的几何尺寸去调节该结构的截止频率，也可以通过调节短截线的尺寸来改变该结构的阻带特性。这种关系能为可调谐矩形环DGS的分析和设计提供有力的指导。

关键词: 缺陷接地结构, 微波滤波器, 时域有限差分法, 截止频率