In this paper, a design technique based on a stepped impedance synthesis is proposed for the first time for the passband and stopband control of band-pass filters in substrate integrated waveguide (SIW) technology. The structure of the band-pass filters is implemented by means of elliptic patterns etched on the top side of the SIW, which work as impedance inverters. The design method consists of previously mapping the height of the elliptic patterns and the phase shift (cut-off angle) of the SIW lines, connected to the input and output ports of the ellipses, as a function of the passband and stopband characteristics of various stepped impedance SIW filters, to then select the design parameters of the band-pass SIW filter that achieve the desired frequency response. This new approach is applied to the design of two fourth-order Chebyshev stepped impedance band-pass SIW filters with different passband and stopband characteristics. One of the band-pass SIW filters is characterized by a fractional bandwidth = 14.5 % and a spurious-free range = 2.8 GHz, while the other filter has a = 22.3 % and a = 1.55 GHz. Both band-pass filters were designed with a SIW TE mode cut-off frequency and a higher passband cut-off frequency fixed at = 2.85 GHz and = 3.9 GHz, respectively. Electromagnetic (EM) simulations showed that the lower passband cut-off frequency can vary with respect to by 13.6 % and that the first spurious frequency can appear higher than by 69.3 %. The measurement results agreed well with the EM simulations, thus confirming that this method can be useful to design high-performance wideband Chebyshev stepped impedance band-pass SIW filters with a high degree of control on the passband and stopband characteristics.

中文翻译：

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一种采用椭圆阶跃阻抗设计的宽带带通衬底集成波导（SIW）滤波器的通带和阻带控制技术

本文首次提出了一种基于步进阻抗合成的设计技术，用于衬底集成波导（SIW）技术中带通滤波器的通带和阻带控制。带通滤波器的结构是通过在 SIW 顶部蚀刻椭圆图案来实现的，其用作阻抗逆变器。该设计方法包括预先映射椭圆图案的高度和连接到椭圆输入和输出端口的 SIW 线的相移（截止角），作为各种通带和阻带特性的函数。阶跃阻抗 SIW 滤波器，然后选择可实现所需频率响应的带通 SIW 滤波器的设计参数。这种新方法应用于具有不同通带和阻带特性的两个四阶切比雪夫步进阻抗带通SIW滤波器的设计。其中一个带通 SIW 滤波器的特征在于分数带宽 = 14.5 % 和无杂散范围 = 2.8 GHz，而另一个滤波器的 a = 22.3 % 和 a = 1.55 GHz。两个带通滤波器均设计有 SIW TE 模式截止频率和固定在 = 2.85 GHz 和 = 3.9 GHz 的较高通带截止频率。电磁 (EM) 模拟表明，下通带截止频率可能会变化 13.6%，并且第一个杂散频率可能会高出 69.3%。测量结果与电磁仿真结果吻合良好，从而证实该方法可用于设计对通带和阻带特性具有高度控制的高性能宽带切比雪夫步进阻抗带通SIW滤波器。