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Out‐of‐band improvement by BPFs with multiple attenuation poles using a condition of variable coupling length of a parallel partially coupled‐line section
Author(s) -
Pokharel Ramesh K.,
Wada Kouji,
Ohno T.,
Hashimoto Osamu
Publication year - 2005
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.21064
Subject(s) - stopband , attenuation , passband , band pass filter , resonator , spurious relationship , microwave , coupling (piping) , microstrip , section (typography) , line (geometry) , filter (signal processing) , wavelength , position (finance) , physics , engineering , electronic engineering , topology (electrical circuits) , optics , electrical engineering , computer science , telecommunications , mathematics , geometry , machine learning , economics , mechanical engineering , finance , operating system
Abstract A combination of two microstrip‐line resonators, which are partially coupled, are considered in a parallel partially coupled‐line bandpass filter (BPF), where one resonator is one half‐wavelength (λ/2) long, and the other (whose one end is grounded) is only one quarter‐wavelength (λ/4) long. Therefore, the length of a coupled‐line section can be varied based on the position of the grounded end. Five conditions of the movable coupling length are simulated, which greatly influences the spurious responses of the BPF. This property is numerically investigated in this paper. The analysis shows that, based on the grounding position, this method is capable of realizing improved out‐of‐band characteristics by locating the multiple attenuation poles in the stopband and improved spurious responses up to five times of the passband frequency (5 f 0 ) of a parallel partially coupled‐line BPF. An empirical model of the BPF is fabricated, and the numerical results are verified via comparison with the experiment. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 4–9, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21064