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Compact high‐selectivity tunable dual‐mode filter with constant bandwidth by adopting frequency‐dependent S‐L coupling
Author(s) -
Zhu JiaMing,
Xue YiFan,
Sun Liang,
Liu Fei,
Deng HonWei
Publication year - 2020
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.32031
Subject(s) - passband , bandwidth (computing) , band pass filter , resonator , stopband , physics , dual mode , band stop filter , materials science , topology (electrical circuits) , optoelectronics , electronic engineering , optics , low pass filter , computer science , engineering , telecommunications , electrical engineering
Abstract A compact high‐selectivity tunable dual‐mode microstrip bandpass filter (BPF) with constant bandwidth is proposed in this letter. Three self‐adaptive transmission zeros (TZs) are generated due to the frequency‐dependent source‐load (S‐L) coupling and intrinsic characteristic of dual‐mode resonator, which can sharpen the skirt and deepen the upper stopband. The passband performance can be mainly determined by the pole separation Δ f of dual‐mode and external quality factor Q e . Finally, a tunable filter with tuning range from 1.15 to 1.65GHz, constant 3 dB absolute bandwidth (ABW 3dB ) of 120 ± 5 MHz is designed and fabricated. The measurement results show good agreement with simulated ones, which confirms the design feasibility.