This article presents a systematic procedure aimed to design continuous profile stopband filters assembled with empty substrate integrated coaxial lines. The coaxial filter is made of five low-cost substrate layers, where the central boards contain the filter profile. This structure exhibits unimodal TEM operation over a wide frequency band, it is not dispersive, it is shielded and cannot be interfered from external signals, and it can be easily integrated with other planar devices. Well-known scattering inverse methods based on the coupled-mode theory have been used for the dimensional synthesis of the proposed topology. Since these dimensions are obtained analytically, no further brute-force optimizations are needed. In particular, a nine-pole elliptic stopband filter operating in the $K_{u}$ band and covering the whole bandwidth of Hispasat 1E communication satellite is shown. The final manufactured filter prototype is large in the longitudinal dimension, but due to its continuous topology, it results to be rather insensitive to fabrication tolerances and errors. Measured results are in good agreement with full-wave simulations. The proposed empty substrate integrated coaxial technology is particularly suitable to realize stopband filters with moderate or wide bandwidths for next-generation satellite applications.

中文翻译：

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用空基板集成同轴线实现的连续剖面阻带滤波器的设计程序

本文介绍了一种系统程序，旨在设计由空基板集成同轴线组装的连续剖面阻带滤波器。同轴滤波器由五个低成本基板层组成，其中中央板包含滤波器轮廓。这种结构在很宽的频带上表现出单峰 TEM 操作，它没有色散，它是屏蔽的，不受外部信号的干扰，并且可以很容易地与其他平面器件集成。众所周知的基于耦合模式理论的散射逆方法已被用于所提出的拓扑结构的维度综合。由于这些尺寸是通过分析获得的，因此不需要进一步的蛮力优化。特别是，显示了一个在 $K_{u}$ 波段工作并覆盖 Hispasat 1E 通信卫星整个带宽的九极椭圆阻带滤波器。最终制造的过滤器原型的纵向尺寸很大，但由于其连续拓扑结构，它对制造公差和错误相当不敏感。测量结果与全波模拟非常吻合。所提出的空基板集成同轴技术特别适合为下一代卫星应用实现具有中等或宽带宽的阻带滤波器。测量结果与全波模拟非常吻合。所提出的空基板集成同轴技术特别适合为下一代卫星应用实现具有中等或宽带宽的阻带滤波器。测量结果与全波模拟非常吻合。所提出的空基板集成同轴技术特别适合为下一代卫星应用实现具有中等或宽带宽的阻带滤波器。