微带交指滤波器通常需要使用接地孔接地，传统的设计方法是在整体建模时再考虑接地孔的影响，导致了接地孔的个数、大小、位置都不确定的多因素、多水平问题，因此可以在设计过程中提前考虑接地孔的影响来避免这些问题。以Ka波段滤波器为案例，分别使用了传统的奇偶模阻抗法、耦合系数和外部品质因数法以及在设计过程中考虑了接地孔的改进方法进行设计。初始设计结果显示，传统方法的中心频率发生偏移，并且其他参数与设计指标相差甚远，而改进方法的中心频率、通带范围以及带外抑制满足指标要求，并且最大插入损耗为3.08 dB，最小回波损耗为10.08 dB，有利于减少后续迭代次数。

Via-holes are usually required to ground for microstrip interdigital filter. The influence of the grounding via-hole is considered when modeling the overall system in traditional design methods, which will lead to the multi-factor and multi-level problem since the number, size and position of the grounding via-holes are uncertain. The problems can be avoided by proposing grounding via-hole effect in microstrip interdigital filter design. Taking Ka-band filter as an example, the traditional odd-even mode impedance method, coupling coefficient and external quality factor method, and the modification method of considering the grounding via-holes in the design process are used to design the filter respectively. The initial design results show that the center frequency of the traditional method is shifted to the left, and other parameters are much different from the design specification. The center frequency, passband range and stop rejection of the modification method meet the requirements of the specification, and the maximum insertion loss is 3.08 dB, the minimum return loss is 10.08 dB, which is helpful to reduce the subsequent iterations.