Theoretical Analysis of Center Frequency and Bandwidth Tunable Resonator Employing Coupled Line and Switches

Kunihiro KAWAI  Hiroshi OKAZAKI  Shoichi NARAHASHI  Mizuki MOTOYOSHI  Noriharu SUEMATSU  

IEICE TRANSACTIONS on Electronics   Vol.E102-C   No.8   pp.612-621
Publication Date: 2019/08/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.2018ECP5074
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
tunable resonators,  coupled line,  microstrip lines,  switches,  

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This paper presents a theoretical analysis of a tunable resonator using a coupled line and switches for the first time. The tunable resonator has the capability to tune its resonant frequency and bandwidth. The resonator has two suitable features on its tunable capability. The first feature is that the resonator retains its resonant frequency during bandwidth tuning. The second feature is that the on-state switch for tuning the bandwidth does not affect the insertion loss at the resonant frequency. These features are theoretically confirmed by its mathematically derived input impedance. The results from electromagnetic simulation and measurement of the fabricated tunable resonator also confirm these features. The fabricated tunable resonator changes the resonant frequency from 2.6 GHz to 6.4 GHz and bandwidth between 9% and 55%.