Two kinds of triple‐band filters based on 90⁰ sector substrate integrated waveguide (SSIW) are firstly investigated. The resonant frequencies of SSIW are deduced by analogy with a circular SIW cavity. By contrast, SSIW cavity is not only easier to suppress higher‐order modes than the circular SIW cavity, but also easier to cascade multiple cavities. Two kinds of miniaturization filters are realized by using dual‐layer and single‐layer half‐mode structures, respectively. Dual‐layer triple‐band filter is realized by using TM₁₁₀, TM₁₂₀, and TM₂₁₀. The single‐layer triple‐band filter based on half‐mode SSIW is proposed for further miniaturization. It adopts higher order modes (TM₁₁₀, TM₁₂₀, and TM₃₁₀) to achieve triple‐band response. Moreover, it introduces a W‐shaped coupling slotline, which not only makes lower original resonant frequencies, but also increases the coupling strengths. Source and load coupling (S‐L‐C) and CSRR are introduced for improving the selectivity of the proposed two filters. Finally, both filters have been fabricated. The measured results are in line with the simulated ones.

中文翻译：

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两个基于900扇区衬底集成波导的小型三频滤波器

首先研究了两种基于90 ⁰扇形衬底集成波导（SSIW）的三频滤波器。类似于圆形SIW腔，推导了SSIW的谐振频率。相比之下，SSIW腔不仅比圆形SIW腔更容易抑制高阶模态，而且更容易层叠多个腔。分别使用双层和单层半模结构可实现两种小型化滤波器。通过使用TM ₁₁₀，TM ₁₂₀和TM ₂₁₀来实现双层三频滤波器。为了进一步小型化，提出了基于半模SSIW的单层三频滤波器。它采用高阶模式（TM ₁₁₀，TM ₁₂₀和TM ₃₁₀）以实现三频响应。此外，它引入了W形耦合缝隙线，不仅降低了原始共振频率，还提高了耦合强度。引入了源和负载耦合（S–L–C）和CSRR，以提高所建议的两个滤波器的选择性。最终，两个滤光片均已制成。测量结果与模拟结果一致。