带抽头的微带交指滤波器初始设计流程

带抽头的微带交指滤波器初始设计方法繁多，但设计不够全面、简洁，同时精度不高，因此给出了一套详细、简洁的初始设计流程。设计步骤为：指标“规范化”，确定低通原型滤波器，求解滤波器阶数，求解归一化电导值，设计抽头的线长和线宽，设计谐振器的线宽，设计非输入输出谐振器的线长，设计相邻谐振器间距，设计输入输出谐振器的线长和抽头的位置，交指滤波器整体建模仿真。最后以Ka波段滤波器为案例进行初始设计，初始设计结果显示中心频率在30.19 GHz附近，通带比29.40~31.00 GHz略大，通带内最大插入损耗为4.22 dB，最小回波损耗为9.32 dB，27.00 GHz和33.40 GHz的带外抑制大于30.00 dB，已经基本满足设计指标，后续只需要稍加优化就能完全满足设计指标，验证了此套设计流程的可行性及其较高的精度。

Initial design procedure of microstrip interdigital filter with tapped-line

There are many initial design methods for microstrip interdigital filter with tapped-line but the design methods are not complate, concise and accurate enough, so a set of initial design flow with completeness and conciseness is given. The design steps are as follows: index "standardization", determine the low-pass prototype filter, determine the order of the filter, determine the normalized conductance value, design tapped line length and width, design resonator width, design non-input/output resonator length, design adjacent resonator spacing, design input/output resonator length and tapped line position, integral modeling and simulation of interdigital filter. Finally, taking the initial design of Ka-band filter as an example, the initial design results show that the center frequency is about 30.19 GHz, the passband range is slightly larger than 29.40-31.00 GHz, the maximum insertion loss is 4.21 dB, the minimum return loss is 9.35 dB, the stopband rejection of 27.00 GHz and 33.40 GHz is more than 30.00 dB, which basically meet the design indexes, only a little optimization is needed to fully meet the design indexes, and the feasibility and high accuracy of the design flow are verified.