Frequency- And Bandwidth-Tunable Absorptive Bandpass Filter

Seong Wook Jeong, Tae Hak Lee, Juseop Lee

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


In this paper, an analytic design method for a frequency- and bandwidth-tunable absorptive bandpass filter is introduced. The presented design method relies on the transformation from the normalized absorptive low-pass filter prototype to a bandpass filter structure with parallel resonators and admittance inverters. The inverter values for producing a predefined frequency response are given in closed-form expressions so that a filter design needs no heuristic approach and can be carried out in an analytic manner. This work also presents a new tunable stub resonator structure capable of changing not only its resonant frequency but also the slope parameter. As the slope parameter can be adjusted, it is allowed to use static inverters in designing a filter whose bandwidth can be tuned. For demonstrating our design method for a reconfigurable absorptive bandpass filter, a third-order filter having the target to have the frequency tuning range from 1.35 to 1.65 GHz and the bandwidth tuning range from 5% to 10% has been designed and measured.

Original languageEnglish
Article number8717621
Pages (from-to)2172-2180
Number of pages9
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number6
Publication statusPublished - 2019 Jun
Externally publishedYes

Bibliographical note

Funding Information:
Manuscript received October 30, 2018; revised February 18, 2019 and April 10, 2019; accepted April 24, 2019. Date of publication May 17, 2019; date of current version June 4, 2019. This work was supported by the National Research Foundation of Korea (NRF) through the Korea Government (MSIT) under Grant NRF-2018R1A2B6006095. This paper is an expanded version from the IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO), Reykjavik, Iceland, August 8–10, 2018. (Corresponding author: Juseop Lee.) S.-W. Jeong and J. Lee are with the Department of Computer and Communications Engineering, Korea University, Seoul 02841, South Korea (e-mail:

Funding Information:
Dr. Lee was a recipient of the Post-Doctoral Research Fellowship from the National Research Foundation.

Publisher Copyright:
© 2019 IEEE.


  • Absorptive filter
  • microstrip line filter structure
  • tunable filter
  • tunable stub resonator

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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