Abstract: To overcome the inexactitude and inconvenience of KQ method and parity module method, this thesis researches a designing method of terminal short-circuited microstrip interdigital filter based on self-mutual capacitance, gives detailed designing steps and example of simulation design. This paper puts forward an improved structure of microwave interdigital filter, this structure adds a microstrip line whose length is λ0/8. This structure makes the 3 dB bandwidth decrease from 100 MB to 40 MB, passband dithering decrease 2.7 dB, stopband attenuation decrease about 2 dB, this simulation result shows that this improved structure is in effect.

Key words: microstrip filter, interdigital filter, terminal short-circuited type, Advanced Design System（ADS）

摘要： 针对微带交指滤波器KQ法及奇偶模阻抗法设计不够精确、不够简便的问题，研究了一种基于自互电容的终端短路式微带交指滤波器的设计方法，给出了详细的设计步骤及仿真设计实例。提出了一种微带交指滤波器的改进结构，该结构通过在交指滤波器的中间耦合节上增加一段λ0/8的微带线，使滤波器的3 dB带宽从100 MB减小到40 MB，带内抖动减小了2.7 dB，阻带衰减增加了2 dB左右，该仿真结果证明了改进结构的有效性。

关键词: 微带滤波器, 交指滤波器, 终端短路式, 先进设计系统（ADS）