Contactless Tuning Plunger and its Application to K-Band Frequency-Tunable Cavity Filter

Seunggoo Nam, Boyoung Lee, Changsoo Kwak, Juseop Lee

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


In this paper, we present a frequency-tunable constant-bandwidth waveguide filter structure with contactless tuning plungers. For the purpose of adjusting the center frequency of the filter, we, for the first time, developed the contactless plungers of waveguide corrugation structure. The new plungers do not require any electrical and mechanical contacts with the waveguide circular resonators, and this allows the plungers to move freely. Although each plunger does not have electrical and mechanical contacts with each resonator, its {Q} -factor is comparable to a conventional resonator with no openings. We have also developed a design method for a frequency-tunable waveguide filter capable of having a constant absolute bandwidth. The tuning plungers are used only for the resonators, and the coupling structures are designed to be static in order to minimize the number of tuning devices. For demonstration, a fourth-order waveguide filter has been designed, fabricated, and measured. The measurement shows that it can be tuned from 19.00 to 19.48 GHz having the absolute bandwidth of 54.5 ± 2.5 MHz.

Original languageEnglish
Article number8715808
Pages (from-to)2713-2719
Number of pages7
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number7
Publication statusPublished - 2019 Jul

Bibliographical note

Funding Information:
Manuscript received August 14, 2018; revised January 7, 2019; accepted March 21, 2019. Date of publication May 15, 2019; date of current version July 1, 2019. This work was supported in part by the Korea Government (MSIT) through the National Research Foundation of Korea under Grant NRF-2018R1A2B6006095 and in part by the Institute for Information and Communications Technology Promotion (IITP) through the Ministry of Science and ICT (Development of Flexible Payload Technologies for Next Satellite Broadcasting and Communications) under Grant 2014-0-00031. (Corresponding author: Juseop Lee.) S. Nam, B. Lee, and J. Lee are with Korea University, Seoul 02841, South Korea (e-mail:

Publisher Copyright:
© 1963-2012 IEEE.


  • Frequency tunable filter
  • gap waveguide

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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