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Wideband and wide stopband superconducting bandpass filter using asymmetric stepped‐impedance resonators connected to open stub
Author(s) -
Luo Chenjie,
Wei Bin,
Wang Xiang,
Lu Xinxiang,
Cao Bisong,
Guo Xubo,
Jiang Linan
Publication year - 2020
Publication title -
international journal of rf and microwave computer‐aided engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.335
H-Index - 39
eISSN - 1099-047X
pISSN - 1096-4290
DOI - 10.1002/mmce.22206
Subject(s) - stopband , stub (electronics) , resonator , band pass filter , wideband , microstrip , acoustics , materials science , passband , transition band , spurious relationship , electronic engineering , insertion loss , return loss , electrical impedance , bandwidth (computing) , optoelectronics , physics , prototype filter , low pass filter , computer science , optics , electrical engineering , telecommunications , engineering , machine learning , antenna (radio)
Abstract A wideband wide stopband filter is designed using asymmetric stepped‐impedance resonators (ASIRs) connected to a large open stub. The capacitive open stub and the parallel‐coupled microstrip line are used to achieve the strong couplings for large fractional bandwidth (FBW). For a wide‐stopband performance, the proposed filter uses ASIRs to improve the high‐order spurious resonant frequency. The first and last resonators of the proposed filter are further optimized to suppress the spurious resonant frequency caused by open stub. The final filter has a 70% FBW centered at 4.87 GHz with 20‐dB‐rejection stopband up to 15.78 GHz (approximately 3.24 f 0 ). The measured insertion loss is less than 0.15 dB and the return loss is better than 17 dB.