A novel in‐line half‐mode substrate integrated waveguide (HMSIW) bandpass filter with interdigital slots has been proposed in this letter. Here, the interdigital slot shows attenuation resonance characteristics and generates a finite frequency transmission zero (TZ). The proposed filter generates two TZs without additional coupling or extra space and exhibits wide stopband characteristics. To validate this method, the in‐line two‐pole quasi‐elliptic bandpass filter is synthesized and fabricated on RT/Duroid 5880 substrate using printed circuit board technology. The experimental results show that center frequency, 3‐dB fractional bandwidth, insertion loss, and return loss are 3.6 GHz, 6.0%, 1.9 and 18 dB, respectively, and are very much similar to the simulated S‐parameters.

中文翻译：

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带有叉指槽的窄带高选择性半模衬底集成波导带通滤波器

本文提出了一种具有叉指槽的新型在线半模衬底集成波导（HMSIW）带通滤波器。此处，叉指槽显示衰减共振特性，并产生有限的频率传输零（TZ）。所提出的滤波器产生两个TZ，而没有额外的耦合或额外的空间，并且具有宽的阻带特性。为了验证该方法，使用印刷电路板技术在RT / Duroid 5880基板上合成并制造了串联式两极准椭圆带通滤波器。实验结果表明，中心频率，3 dB分数带宽，插入损耗和回波损耗分别为3.6 GHz，6.0％，1.9和18 dB，与模拟S参数非常相似。