A class of input-reflectionless low-pass filter (LPF) using a multilayered diplexer-based architecture is presented. It consists of two signal-transmission parts: 1) a reflective-type LPF network built with an open-ended microstrip resonator and a shunt microstrip section and 2) a resistively terminated wide-band microstrip-to-microstrip vertical transition. Thus, based on the in-band transmission poles of the wideband transition at which the RF input signal energy not transmitted by the LPF part is dissipated by the terminating 50- $\Omega $ resistor, a higher selectivity LPF response with broadband reflectionless behavior is attained. To further increase the stopband bandwidth, as well as the attenuation levels and cut-off slope sharpness, in-series cascaded multi-LPF unit designs are engineered. The main RF operational principles and theoretical design examples of the proposed input-reflectionless LPF approach are detailed. Moreover, for practical validation purposes, a two-layered two-LPF unit microstrip prototype with extended stopband and broadband input-reflectionless characteristics is designed, fabricated, and tested.

中文翻译：

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基于多层双工器的拓扑结构上的输入无反射低通滤波器

介绍了一类使用多层双工器架构的输入无反射低通滤波器 (LPF)。它由两个信号传输部分组成：1) 一个反射型 LPF 网络，由一个开放式微带谐振器和一个并联微带部分构成；2) 一个电阻端接的宽带微带到微带垂直过渡。因此，基于宽带转换的带内传输极点，LPF 部分未传输的 RF 输入信号能量在该极点处被端接 50 Ω 电阻器耗散，具有宽带无反射行为的更高选择性 LPF 响应为达到。为了进一步增加阻带带宽，以及衰减水平和截止斜率锐度，设计了串联级联多 LPF 单元。详细介绍了所提出的无输入反射 LPF 方法的主要 RF 操作原理和理论设计示例。此外，出于实际验证的目的，设计、制造和测试了具有扩展阻带和宽带输入无反射特性的两层两 LPF 单元微带线原型。