基于DGS的紧凑型低通滤波器

A compact fifth⁃order low⁃pass filter based on DGS

文中提出一种基于缺陷地结构的新型低通滤波器。其由位于微带结构顶部的加宽微带线、位于接地层中的经典哑铃型缺陷地结构(DGS)和蛇形缝隙缺陷地结构(DGS)组成,结构设计紧凑,容易调整。文中选用0.01 dB等波纹的切比雪夫型低通滤波器,分别采用哑铃型DGS、蛇形缝隙DGS替换LPF原型电路中的电感,加宽微带线替换并联电容,同时将加宽微带线产生的寄生电感考虑进去。哑铃型DGS产生的高频衰减点加宽阻带,蛇形缝隙DGS提供的低频衰减点使得通带到阻带陡峭过渡。实验结果表明,所设计的截止频率为2.54 GHz的低通滤波器具有明显的截止频率响应,通带内插损均在0.9dB以下,阻带抑制均在21dB以下。经实物加工测试验证,所设计的低通滤波器实际结果与仿真结果基本一致,具有可行性。

A novel low⁃pass filter based on DGS(defective ground structure)is proposed,which consists of a widened microstrip line on top of the microstrip structure,a classical dumbbell⁃shaped defect ground structure(DGS)and a serpentine slot defect ground structure in the ground plane.The structure is compact and easy to adjust.In this paper,a 0.01 dB equal⁃ripple Chebyshev⁃type low⁃pass filter is used,and the dumbbell⁃shaped DGS and the serpentine⁃shaped gap DGS are used to replace the inductor in the LPF prototype circuit,and the widened microstrip line replaces the parallel capacitor,and the parasitic inductance generated by widening the microstrip line needs to be taken into account.The high⁃frequency attenuation point generated by the dumbbell⁃shaped DGS widens the stopband,and the low⁃frequency attenuation point provided by the serpentine⁃shaped gap DGS makes the pass⁃to⁃stopband a steep transition.Experiments show that the designed low⁃pass filter with a cutoff frequency of 2.54 GHz has an obvious cutoff frequency response,the insertion loss in the passband is below 0.9 dB,and the stopband suppression is below 21 dB.The actual results are basically consistent with the simulation results,which verifies the feasibility of the design.