Frequency- A nd Bandwidth-Tunable Bandstop Filter Containing Variable Coupling between Transmission Line and Resonator

Seong Wook Jeong, Juseop Lee

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


This paper presents a frequency- A nd bandwidth-tunable bandstop filter using substrate-integrated wave-guide (SIW) resonators. For designing such a filter, this paper also presents a tunable coupling structure between a microstrip line and an SIW resonator for obtaining the bandwidth tuning capability. The coupling structure has two coupling slots between the microstrip line and the resonator, and the phase shift between the two slots determines the overall external coupling value of the resonator. This external coupling value can be controlled by making use of a phase shifter, which in turn makes it possible to adjust the bandwidth of a bandstop filter. A thorough mathematical analysis is shown using the equivalent circuit model of the presented coupling structure, and it has been verified by measuring an SIW resonator containing the presented structure. The presented tunable coupling structure has also been applied to a design of bandstop filter that can be tuned from 2.8 to 3.4 GHz. The measured results at 3.1 GHz show that the bandwidth can be tuned from 0 (all-pass) to 96 MHz reaching the attenuation level of 44 dB.

Original languageEnglish
Article number8068228
Pages (from-to)943-953
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number2
Publication statusPublished - 2018 Feb

Bibliographical note

Funding Information:
Manuscript received November 16, 2016; revised April 19, 2017 and July 6, 2017; accepted August 27, 2017. Date of publication October 16, 2017; date of current version February 5, 2018. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning under Grant NRF-2015R1C1A1A02036754. (Corresponding author: Juseop Lee.) The authors are with the Department of Computer and Communications Engineering, Korea University, Seoul 02841, South Korea (e-mail: juseoplee@

Publisher Copyright:
© 2017 IEEE.


  • All-pass filter
  • bandstop filter
  • bandwidth tunable
  • frequency tunable
  • substrate-integrated waveguide (SIW) resonator

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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