In this paper, a novel four-band diplexer using defected ground structures with compact size, low insertion loss and high isolation is presented. To begin with, there are 16 defected ground stepped impedance resonators (DSIRs) controlling four passbands characteristics. Every four DSIRs can generate one passband. Then, four different DSIRs use the same feeding line. According to the group delay, we can determine the relative physical position of the first resonator. For the demonstration, a four-band diplexer operating at 2.45/4.2 and 3.5/5.2 GHz with the fractional bandwidths of 10, 7, 6.2 and 5% is designed and fabricated. Finally, measured results agree well with simulated results.

中文翻译：

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使用有缺陷的接地结构的紧凑型四频段双工器

在本文中，提出了一种采用缺陷接地结构的新型四频段双工器，具有紧凑的尺寸、低插入损耗和高隔离度。首先，有 16 个有缺陷的接地阶跃阻抗谐振器 (DSIR) 控制着四个通带特性。每四个 DSIR 可以产生一个通带。然后，四个不同的 DSIR 使用相同的馈线。根据群延迟，我们可以确定第一谐振器的相对物理位置。为了演示，设计和制造了一个工作在 2.45/4.2 和 3.5/5.2 GHz 的四频段双工器，其部分带宽为 10%、7%、6.2% 和 5%。最后，测量结果与模拟结果非常吻合。