In this letter, we present analytic approaches to obtain a wide upper stopband and to reduce the magnitude of the electric field intensity in designing a bandpass filter using the fundamental mode of post-loaded substrate-integrated waveguide (SIW) resonators. As the filter is made with two commercially available substrates, there are two dielectric and three ground layers. This letter particularly shows that the ground layer in the middle has an impact on the upper stopband and the electric field intensity and proposes a methodology to control them. For demonstrating our new approach, we have designed a third-order filter centered at 5 GHz with the bandwidth of 330 MHz.

中文翻译：

---

具有宽上阻带和降低的电场强度的后载基板集成波导带通滤波器

在这封信中，我们提出了在使用后载基板集成波导 (SIW) 谐振器的基模设计带通滤波器时获得宽上阻带和降低电场强度幅度的分析方法。由于滤波器由两个市售基板制成，因此有两个介电层和三个接地层。这封信特别说明中间的接地层对上阻带和电场强度有影响，并提出了控制它们的方法。为了演示我们的新方法，我们设计了一个以 5 GHz 为中心、带宽为 330 MHz 的三阶滤波器。