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International Journal of Antennas and Propagation
Volume 2017, Article ID 3915709, 6 pages
Research Article

A Frequency-Tunable SRR-Adopted Two-Pole Waveguide Filter Operating below the Cutoff Frequency

1Future Industry Technology Center, IBITP, 12 Gaetbeol-ro, Yeonsu-gu, Incheon 21999, Republic of Korea
2Electronic Engineering, Chosun University, 309 Pilmundae-ro, Dong-gu, Gwangju 61452, Republic of Korea

Correspondence should be addressed to Soon-soo Oh;

Received 6 March 2017; Accepted 23 March 2017; Published 6 April 2017

Academic Editor: Luciano Tarricone

Copyright © 2017 Wook-Ki Park et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A frequency-tunable filter operating below the cutoff frequency of a metallic hollow waveguide is proposed, which has two-pole bandpass characteristics and incorporates a split-ring resonator (SRR). The tuning procedure is achieved by inserting two metal screws. The screws adjust the magnetic- field passing through the center of the SRR. The effect of SRR orientation was investigated and the optimum orientation proposed. Our results indicated an operating frequency range of 2.0 to 2.35 GHz, which is lower than the cutoff frequency of the waveguide of 4.9 GHz by more than 2.55 GHz. The proposed filter could be utilized for communication, such as software-defined radio (SDR) systems.