In this letter, a general approach to synthesize arbitrary order dual-band narrow-band bandstop filter (BSF) is proposed. Simple formulas are derived to calculate the design parameters for the filter. To validate the method, a third-order dual-band BSF using substrate integrated waveguide (SIW) technology is fabricated. Taking the advantage of the high Q SIW resonators, the fabricated filter shows good stopband suppression. The measured center frequencies of the filter are 6.81 and 7.213 GHz, and the corresponding relative 3-dB bandwidths are 4.6% and 4.1%.

中文翻译：

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SIW双频窄带带阻滤波器的综合与设计

在这封信中，提出了一种综合任意阶双频窄带带阻滤波器（BSF）的通用方法。导出简单公式即可计算滤波器的设计参数。为了验证该方法，制造了使用衬底集成波导（SIW）技术的三阶双频BSF。利用高Q SIW谐振器的优势，所制造的滤波器表现出良好的阻带抑制能力。测得的滤波器中心频率为6.81和7.213 GHz，相应的3 dB相对带宽为4.6％和4.1％。