A multiwideband bandpass filter (MW-BPF) using a quad cross-stub stepped impedance resonator (QC-SSIR) was simulated, fabricated, and measured. The proposed QC-SSIR is designed on a four-series arrangement of crossed open stub (COS) structures where each open stub is developed with a step impedance resonator (SIR) structure to generate a wide bandwidth. Compared to the COS resonator, the QC-SSIR has a wider fractional bandwidth and good transmission coefficients and is compact. ABCD matrix analysis is used to investigate the filter structure. Furthermore, the MW-BPF is designed on an FR4 microstrip substrate with εr = 4.4, thickness h = 1.6 mm, and tan δ = 0.0265. The results show that the proposed MW-BPF using a QC-SSIR achieves transmission coefficients/fractional bandwidths of −0.60 dB/49.3%, −1.49 dB/18.7%, and −1.93 dB/13.9% at 0.81 GHz, 1.71 GHz, and 2.58 GHz, respectively. Furthermore, to reduce the filter size, a folded QC-SSIR (FQC-SSIR) structure was also proposed. The results show that the proposed MW-BPF using an FQC-SSIR achieves transmission coefficients/fractional bandwidths of −0.57 dB/49.6%, −1.21 dB/17.7%, and −1.76 dB/12.5% at 0.82 GHz, 1.80 GHz, and 2.62 GHz, respectively. The size of the proposed MW-BPF using an FQC-SSIR is reduced by up to 46% compared with the MW-BPF using a QC-SSIR. Finally, the performance of the simulated MW-BPF based on the QC-SSIR and FQC-SSIR was in good agreement with the measurement results.

中文翻译：

---

基于折叠式四叉截线步进阻抗谐振器的多宽带带通滤波器

模拟，制作和测量了使用四叉截线步进阻抗谐振器（QC-SSIR）的多宽带带通滤波器（MW-BPF）。所提出的QC-SSIR是在交叉开路短截线（COS）结构的四系列结构上设计的，其中每个开路短截线均采用阶跃阻抗谐振器（SIR）结构进行开发以产生较宽的带宽。与COS谐振器相比，QC-SSIR具有更宽的分数带宽和良好的传输系数，并且结构紧凑。ABCD矩阵分析用于研究过滤器结构。此外，MW-BPF设计有FR4微带基板上ε R = 4.4，厚度ħ  = 1.6毫米，黄褐色δ = 0.0265。结果表明，采用QC-SSIR的拟议MW-BPF在0.81 GHz，1.71 GHz和1.01 GHz时实现了-0.60 dB / 49.3％，-1.49 dB / 18.7％和-1.93 dB / 13.9％的传输系数/分带宽。分别为2.58 GHz。此外，为了减小滤波器尺寸，还提出了折叠式QC-SSIR（FQC-SSIR）结构。结果表明，采用FQC-SSIR的拟议MW-BPF在0.82 GHz，1.80 GHz和0.82 GHz时可实现-0.57 dB / 49.6％，-1.21 dB / 17.7％和-1.76 dB / 12.5％的传输系数/分带宽。分别为2.62 GHz。与使用QC-SSIR的MW-BPF相比，使用FQC-SSIR的拟议MW-BPF的尺寸最多减少了46％。最后，基于QC-SSIR和FQC-SSIR的模拟MW-BPF的性能与测量结果吻合良好。