Bandpass Filters Using Tunable Half-Wavelength Resonators with Transmission Zeros

Kouji WADA  Shinya WATANABE  Ryousuke SUGA  Osamu HASHIMOTO  

IEICE TRANSACTIONS on Electronics   Vol.E88-C   No.1   pp.68-76
Publication Date: 2005/01/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.1.68
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Trends of Microwave and Millimeter-Wave Passive Circuit Components and Technologies for Improvement of Characteristics)
tunable half-wavelength resonator,  tap-coupling,  bandpass filter,  transmission zero,  

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This paper focuses on the characteristics of tunable half-wavelength resonators and their applications to bandpass filters (BPFs). First, the resonance characteristics of various tunable half-wavelength resonators are examined for the tunabilities of transmission zeros and the center frequency of the proposed BPFs. We examine four types of tunable half-wavelength resonators, namely, an end-coupling resonator and three types of tap-coupling resonators. Secondly, the proposition and design of two types of BPFs using acquired resonators are carried out. The fabrication and experimental application of the resonators and designed BPFs are also performed based on coplanar waveguide (CPW) technologies. Their calculated and measured results are compared with each other. The results show that tunabilities of the transmission zero and the center frequency of the proposed BPF are obtained as expected.