Ultra-wide Stopband Waveguide Low-pass Filter Design Based on Asymmetric Inductance Unit Structure

This paper presents a new design method for ultra-wide stopband waveguide low pass filter based on asymmetric inductance unit structure. Firstly, the initial design of the filter can be completed quickly through the inductive unit and capacitor unit circuit simulation and the three-dimensional electromagnetic simulation. Secondly, through the analysis of the field distribution of the typical resonance frequency of the filter parasitic passband, it is determined that the high-frequency parasitic oscillation of the filter inductance unit is the main reason for the deterioration of the filter stopband. Therefore, based on the design idea of the asymmetric inductance unit structure, the staggered distribution characteristics of the out-of-band resonance frequency points of the filter are optimized, and the structure design of the X-band wide stopband waveguide low-pass filter is realized. Simulation and measurement results show that the filter has a passband frequency response of 9.7~11GHz, and the stopband frequency range of 11.8GHz~43GHz achieves the suppression greater than 50dB.