In this article, we describe several alternative inline implementations for combline filters with transmission zeros (TZs) located both below and above the passband. A systematic design procedure is also presented using a lumped-element equivalent circuit. Following the design procedure that we propose, up to $N+1$ TZs can be implemented with an inline filter of order $N$ . The generation of the TZs is explained physically in terms of mixed inductive and capacitive couplings. Several filters are also manufactured and tested. Good agreement between the measured and simulated results is demonstrated, thereby fully validating the new filter concepts.

中文翻译：

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N 阶串联组合滤波器，具有多达 N + 1 个传输零点


在本文中，我们描述了梳状线滤波器的几种替代内联实现，其传输零点 (TZ) 位于通带下方和上方。还使用集总元件等效电路提出了系统设计过程。按照我们建议的设计过程，最多可以使用 $N$ 级的内联滤波器来实现 $N+1$ TZ。 TZ 的产生可以通过混合电感和电容耦合进行物理解释。还制造并测试了多种过滤器。测量结果与模拟结果之间具有良好的一致性，从而充分验证了新的滤波器概念。