基于微扰通孔法实现SIW宽阻带带通滤波器的设计

Design of SIW Wide Stopband Bandpass Filter Based on Perturbation Via Method

在单层结构中,滤波器采用直角耦合方式往往会破坏高次模TE102/TE201场的分布特性,导致场产生恶化,从而影响抑制效果。针对此问题,提出了加载金属微扰通孔的方法扰动场的分布特性,从而修复模式的本征抑制,最终抑制了TE102/TE201模的谐波通带。基于此方法,研究了二阶基片集成波导(Substrate Integrated Waveguide,SIW)带通滤波器的阻带宽度延伸及带外抑制优化的设计,中心频率f_(0)=9 GHz,相对带宽FBW为2.44%,插入损耗低于1.3 dB,回波损耗优于20 dB,阻带延伸至18.93 GHz时,带外抑制优于20 dB。最后,分别设计、制作了三阶、四阶SIW带通滤波器进行实物验证,实测的阻带宽度均超过2.05f0,且抑制深度均优于30 dB,验证了该设计方法的可行性和准确性。

In single-layer structure,the filter using right-angle coupling mode often destroys the distribution characteristics of the high-order mode TE102/TE201 fields,resulting in the worsening of the field generation,thus affecting the suppression effect.To address this problem,a method of loading metal perturbation via is proposed to disturb the distribution characteristics of the field,so that the harmonic passband of TE102/TE201 mode is suppressed,and the filter obtains wide stopband and high out-of-band suppression performance.Based on this method,the stopband width extension and out-of-band suppression optimization design of second-order SIW bandpass filter are studied.The center frequency f0=9 GHZ,the relative bandwidth FBW is 2.44%,the insertion loss is less than 1.3 dB,and the return loss is better than 20 dB.When the stopband extends to 18.93 GHz,the out-of-band suppression is better than 20 dB.Finally,the third-order and fourth-order SIW bandpass filters are designed and fabricated respectively for physical verification.The measured stopband width is more than 2.05f0,and the suppression depth is better than 30 dB,which verifies the feasibility and accuracy of the design method.