This article presents different physical arrangements of filters using conical posts as the basic element of design. The proposed resonator is similar to that of the classical combline filter, however, in this case, a conical post (truncated cone) is exploited. A hollowed enclosure is positioned on top of a rectangular metallic cavity for housing the upper part of the conical resonating post. Considering that the post upper radius is smaller than the post lower radius, an enclosure having the same dimensions as the resonating post can be taken. This results in a housing that can also work as an additional resonator for another cavity. As a result, cavities can be piled in a vertical arrangement and the conical post of each cavity is also used for housing the post of the cavity below it. Mixed vertically and/or horizontally arrangements are also feasible. More compact structures can be achieved with the possibility to obtain different footprints while maintaining similar unloaded $Q$ -factors than conventional combline filters. The structure also has the advantage of having a wider spurious-free range than the classical combline filter configuration (cylindrical post inside a rectangular cavity). Enhanced responses with higher rejections are also possible thanks to the introduction of transmission zeros. Several different filter configurations are presented in this article: 3-order filter and 4-order filter. The design procedure is explained for both of them. A 4-order filter has been manufactured using additive manufacturing techniques and measured in order to validate the proposed structure.

中文翻译：

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基于锥形柱的 3D 打印紧凑型带通滤波器

本文介绍了使用锥形柱作为基本设计元素的过滤器的不同物理布置。建议的谐振器类似于经典梳状线滤波器的谐振器，但是，在这种情况下，使用了锥形柱（截锥）。中空的外壳位于矩形金属腔的顶部，用于容纳锥形谐振柱的上部。考虑到柱上半径小于柱下半径，可以采用与谐振柱具有相同尺寸的外壳。这导致外壳也可以用作另一个腔的附加谐振器。结果，空腔可以垂直排列并且每个空腔的锥形柱也用于容纳其下方的空腔的柱。混合的垂直和/或水平布置也是可行的。可以实现更紧凑的结构，同时保持与传统梳状线滤波器相似的无负载$Q$ 因子的可能性。该结构还具有比传统梳状线滤波器配置（矩形腔内的圆柱柱）更宽的无杂散范围的优点。由于引入了传输零点，还可以增强具有更高拒绝的响应。本文介绍了几种不同的滤波器配置：3 阶滤波器和 4 阶滤波器。对它们的设计过程进行了解释。已经使用增材制造技术制造了一个 4 阶滤波器并进行了测量，以验证所提出的结构。可以实现更紧凑的结构，同时保持与传统梳状线滤波器相似的无负载$Q$ 因子的可能性。该结构还具有比传统梳状线滤波器配置（矩形腔内的圆柱柱）更宽的无杂散范围的优点。由于引入了传输零点，还可以增强具有更高拒绝的响应。本文介绍了几种不同的滤波器配置：3 阶滤波器和 4 阶滤波器。对它们的设计过程进行了解释。已经使用增材制造技术制造了一个 4 阶滤波器并进行了测量，以验证所提出的结构。可以实现更紧凑的结构，同时保持与传统梳状线滤波器相似的无负载$Q$ 因子的可能性。该结构还具有比传统梳状线滤波器配置（矩形腔内的圆柱柱）更宽的无杂散范围的优点。由于引入了传输零点，还可以增强具有更高拒绝的响应。本文介绍了几种不同的滤波器配置：3 阶滤波器和 4 阶滤波器。对它们的设计过程进行了解释。已经使用增材制造技术制造了一个 4 阶滤波器并进行了测量，以验证所提出的结构。