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Synthesis of X‐band trisection bandpass filters using hybrid structures of λ/4 and λ/2 resonators
Author(s) -
Anwar Muhammad Sufian,
Nikolaou Symeon,
Nawaz Hamza,
Abbasi Muhammad Ali Babar
Publication year - 2019
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.31838
Subject(s) - passband , band pass filter , stopband , resonator , prototype filter , topology (electrical circuits) , distributed element filter , bandwidth (computing) , physics , electronic engineering , transition band , insertion loss , microstrip , electronic filter topology , elliptic filter , optics , computer science , low pass filter , engineering , telecommunications , electrical engineering
This paper presents the design of compact cross‐coupled microstrip trisection bandpass filters based on the hybrid structures of quarter‐wavelength (λ/4) and half‐wavelength (λ/2) resonators. The desired cross‐couplings for transmission zeros (TZs) are realized by parallel‐coupled transmission‐line sections (J‐inverter) or coupled via sections (K‐inverter) of λ/4 resonators. The main‐line couplings, on the other hand, are formed by mixed‐coupled λ/4 and λ/2 resonators. To validate the proposed hybrid configurations, two X‐band trisection filters with 6.5% and 6.2% fractional bandwidth were designed. The first filter generates a TZ below the passband, while the second one produces a TZ above the passband. Minimum insertion loss of 1.7 dB and 1.5 dB was observed for the two trisection filters, respectively, while the hybrid configurations caused significant size reduction in the overall filter size. Moreover, the first spurious response for the proposed filter topologies was pushed to 3fo, resulting in a wide stopband.