基于消失模耦合的脊波导滤波器设计方法

Design Method of the Ridge Waveguide Filter with Evanescent Mode Coupling

针对传统脊波导滤波器设计中没有考虑耦合结构频率特性导致设计精度不高的问题,文中提出了一种基于消失模耦合的脊波导滤波器设计方法。该方法将工作于消失模状态下的矩形波导结构等效为频变阻抗变换器模型,通过等效电路变换将耦合结构的频变特性影响转换为对传输线谐振腔电抗斜率参数的影响,采用逐级仿真策略确定滤波器结构尺寸,避免了耗时的全波仿真优化。最后,通过一个4阶切比雪夫特性的脊波导滤波器设计实例进行验证。全波仿真结果显示了与理论设计相同的通带内等波纹特性,验证了所提方法的有效性。

In the design of traditional ridged waveguide filter,the design precision is not high because of the lack of the frequency characteristics of the coupling structure.This paper presented a design method for the ridge waveguide filter with evanescent mode coupling.The rectangular waveguide working in the evanescent mode was equivalent to a frequency dependent impedance inverter model.By establishing an equivalent circuit model,the frequency variation of the coupling structure was converted to influence the reactance slope parameters of the resonator.The filter structure size was determined by the step by step simulation strategy to avoid the time-consuming full wave simulation optimization.Finally,a ridge waveguide filter with four orders Chebyshev response was designed.Full wave simulation results showed the same bandpass equiripple property as the theoretical design and verifyied the validity of the method.