提 出了一种新型的混合共面波导和微带结构的超宽带带 通滤波器.通过将中间微带替换成交指耦合线,在下通带边缘产生一个传输零点,使得滤波器的选择性得到极大提升.此外,引入了耦合短路枝节以进一步提升其选择性和带外特性.实测结果表明,提出的滤波器具有不错的带内和带外性能.其具有陡峭的选择性,尺寸紧凑(0.49 λ g×0.47 λ g),插入损耗低,且上阻带宽.该滤波器的相对带宽达123%(2.75~11.55 GHz),回波损耗优于15 dB.并且,最终的加工实测结果和仿真结果基本一致.%A novel ultra-wideband BPF using hybrid CPW and microstrip structure is proposed in this paper. The middle mi crostrip is replaced by an interdigital coupled-line to generate a transmission zero at low frequency. As a result, the selectivity is significantly improved. Moreover, the coupling short stubs(CSS) are used to further improve its selectivity and out-of-band performances. The measured results show that the proposed filter possesses satisfactory out-of-band and in-band performances such as sharp roll-off, compact size(0.49 λg×0.47 λg), low insertion loss, and wide upper stopband. The proposed filter has wide fractional bandwidth of 123%(2.75~11.55 GHz), and a return loss of better than 15 dB is achieved. Besides, the measured results of fabricated filter agree well with the simulation.
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