横向双模双频滤波器设计

Dual-band transversal bandpass filters using dual-mode resonator

基于横向滤波器耦合结构,采用支节加载双模谐振器,设计了中心频率位于1.57 GHz(GPS应用)与2.4GHz(WLAN应用)的双频微带滤波器。由短路支节加载双模谐振器形成第一个通带,开路支节加载双模谐振器形成第二个通带,两个谐振器被输入/输出馈线隔离,每个通带的中心频率与带宽可以单独调节。测试结果表明:两个通带内的最小插损分别为2.18,1.35 dB,3 dB带宽分别为5.2%,6.8%,回波损耗均小于16 dB,三个传输零点分别位于1.28,2.08,2.71 GHz处。该滤波器具有尺寸小、带外选择性好等优点。

Novel compact dual-band microstrip transversal bandpass filters located at 1.57 GHz（GPS application） and 2.4 GHz（WLAN application） using short-circuited and open-circuited stub-loaded half wavelength resonators were presented. The short-circuited stub-loaded resonator and open-circuited stub-loaded resonator achieved the first and second passband respectively. With the two resonators separated by input/output（I/O） feedline, the central frequencies and bandwidth of every passband were controlled independently. The measured minimum insertion losses are 2.18 dB and 1.35 dB, and 3 dB fractional bandwidths are about 5.2% and 6.8% at the first and second passband respectively. The return losses of two passbands are better than 16 dB. Three transmission zeros are realized at 1.28, 2.08 and 2.71 GHz. The filter has the advantages of compact size and high selectivity.