频率可控的小型化四频带滤波器设计

Miniaturized Quad-band Bandpass Filter with Controllable Frequencies

提出了一款新型平面四频带滤波器。首先设计了一个频率可控的四模谐振器,当外接激励时,该谐振器产生4条不同的谐振路径,通过控制4条不同谐振路径的长度,实现了对4个频带的独立控制。由于4条不同谐振路径共用了一段微带传输线,即有一段公共的传输路径,从而实现了滤波器小型化的目的。然后利用该谐振器设计了一款频率独立可控的小型化四频带滤波器。该滤波器尺寸为0.1λg×0.11λg(11.2mm×11.7mm),4个通带的中心频率为1.6/3.5/5.0/7.2GHz,回波损耗小于15dB。6个传输零点增加了滤波器的频率选择性和带外的频率抑制水平,测试和仿真结果吻合。

A new planar quad-band bandpass filter was proposed.Firstly,aquad-mode resonator with controllable resonance frequencies was designed.When the quad-mode resonator is under input excitation,four different resonance paths are generated.By controlling the length parameters of the four different resonance paths,the resonance frequencies can be individually controlled.Since the four different resonance paths share a same micro-strip transmission line,in other words,they share a common resonance path,the purpose of filter circuit size miniaturization is achieved.Then by utilizing this resonator,a compact quad-band bandpass filter with controllable frequencies is designed and presented.The circuit size is 0.1λg×0.11λg（11.2mm×11.7 mm）with the band center frequencies of 1.6/3.5/5.0/7.2GHz and the return losses are better than 15 dB.Six transmission zeros enhance the frequency selectivity and out-of-band rejection levels.The test results of the filter are consistent with the simulation results.