基于微带贴片谐振器的高选择性双模双通带带通滤波器的研究

摘要

High-selectivity dual-mode dual-band bandpass filters using microstrip patch resonator and the method of mode analysis are proposed. The closed form solutions of the guided mode field of the microstrip patch resonator and mode constitution are given. The microstrip patch resonator is fed by microstrip quasi-rectangular rings which also work in two degenerate modes, providing the second passband. Compared with the existing dual band bandpass filters, the full wave analysis and measured results show that the number of transmission zeros of the filters designed in this paper is increased by two times. The filter has eleven transmission zeros, suppressing the parasitic passband. The band rejection reaches about 20dB while the insertion loss is only 1.2dB. Furthermore, these structures are suitable for the miniaturization of filters.%本文提出了基于微带贴片谐振器的高选择性双模双通带带通滤波器及一种模式分析算法.首次利用该算法分析了微带贴片的模式组成,计算了导模场的闭式解.微带贴片的耦合馈线同时作为谐振单元构成第二个通带,减小了结构尺寸.全波仿真分析(full wave analysis)结果及测试数据表明,与现有的双模双通带带通滤波器相比,本文设计的滤波器传输零点个数增加了2倍,达到11个,带外抑制度达到20dB,带内插损较小,仅为1.2dB,抑制了寄生通带.同时设计的拓扑结构复杂度较低,利于滤波器的小型化.