This article presents a highly selective dual‐passband filter based on stepped‐impedance‐resonator (SIR) and mixed electromagnetic coupling. First, the surface area of the filter is effectively reduced by the triangular topology. Second, four controllable transmission zeros are introduced by source‐load coupling feed and mixed electromagnetic, which increases the selectivity of the filter. Third, a perturbation structure is added to independently control the resonance points of each passband. Finally, the improved defect ground structure (DGS) is integrated to obtain wide stopband rejection. The measured S‐parameters are well agreement with the simulated results, which show that the center frequencies of the two passbands are 2.4 GHz and 5.2 GHz; and the passband insertion losses are 0.85 dB and 1.6 dB; and the relative bandwidths are 14.6% and 5.7%, respectively. Besides, the structure is with six transmission zeros, and 20 dB suppression for the third harmonic and the fourth harmonic are achieved. Compared with the traditional SIR double‐passband filter, this filter has many advantages, such as simple design, small size, small insertion loss, controllable frequency, high selectivity, and high spurious suppression.

中文翻译：

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具有高选择性和宽阻带抑制能力的双频滤波器

本文介绍了一种基于步进阻抗谐振器（SIR）和混合电磁耦合的高选择性双通带滤波器。首先，通过三角形拓扑有效地减小了过滤器的表面积。其次，通过源-负载耦合馈电和混合电磁引入了四个可控的传输零点，从而提高了滤波器的选择性。第三，增加了扰动结构以独立地控制每个通带的谐振点。最后，集成改进的缺陷接地结构（DGS），以获得宽阻带抑制比。测得的S参数与仿真结果非常吻合，表明两个通带的中心频率分别为2.4 GHz和5.2 GHz。通带插入损耗分别为0.85 dB和1.6 dB；相对带宽分别为14.6％和5。分别为7％。此外，该结构具有六个传输零，并且实现了针对三次谐波和第四谐波的20dB抑制。与传统的SIR双通带滤波器相比，该滤波器具有许多优点，例如设计简单，尺寸小，插入损耗小，频率可控，选择性高以及杂散抑制高。