This paper presents two different dual-band cavity filters based on the frequency transformation. The cavity filters have two different configurations. The one is presented by directed coupling between adjacent resonators, and the other one is presented by introduced cross coupling between nonadjacent resonators to generate a pair of transmission zeros. At first, according to the filter specification the coupling coefficients between resonators and the external quality factors are calculated and obtained. Then the model of the dual-band cavity filters are established with Ansoft HFSS, the simulation result agrees well with the result of equal circuit in ADS, indicating that this method is correct and feasible. Finally, the comparison between the cascade type structure and cross coupling type structure shows that the later has more excellent stopband performance.%该文基于频率变换的方法设计了两种结构的双通带的腔体滤波器,一种是通过谐振器之间直接耦合实现的；另一种是在谐振器之间引入交叉耦合实现的,从而达到产生传输零点的目的.首先根据设计指标,采用频率变换的方法,计算得到谐振器间的耦合系数和外部Q值,然后利用Ansoft HFSS建立同轴腔体滤波器的模型并进行仿真,仿真结果与ADS中等效电路得到的理论结果基本吻合,从而验证了这种方法的正确性.最后通过对级联型结构与交叉耦合型结构双通带腔体滤波器的比较,得出后者比前者具有更好的带外抑制特性.
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