Miniaturized Narrow Band-pass Filter with λg/4 Short Stubs Using S-Shaped Folded Coupling Structure

크기가 축소된 S 형태의 Folded 커플링 구조를 이용한 λg/4 단락형 협대역 스터브 대역통과 여파기

Yoon, Ki-cheol;Kim, Seong-cheol

  • Received : 2015.09.03
  • Accepted : 2015.09.30
  • Published : 2015.10.31


In this paper, the reduced size in horizontal sizes of the narrow band pass filter (BPF) with λg/4 short stub using S shaped folded coupling structure is presented. This BPF with narrow bandwidth show flexible bandwidth with variation of the position of the stubs using the Qe(external quality factor) without changing the impedance value. On the other hand, by replacing the horizontal quarter-wavelength transmission lines with the equivalent S shaped coupled line, the BPF with reduced the size of horizontal can be realized. The proposed BPF shows the insertion loss of 1.46 dB and the return loss of 16.5 dB with bandwidth of 3.4 % at the center frequency of 5.8 GHz, respectively.


Narrow Bandwidth;Short Stub;S-Shape;Miniaturized Size;Coupling Structure


  1. Y. G. Choi and B. K. Kim, "Design of a 5.8 ㎓ broad band-pass filter with second of harmonics suppression using the open stubs," J. Korean Ins. Electromagnetic Engineering and Science, vol. 18, no. 10, pp. 1107-1116, Oct. 2007.
  2. J. S. Hong and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, John Wiley & Sons, 2001.
  3. K. C. Yoon and J. C. Lee, "Design of a 5.8 GHz narrow band-pass filter with second harmonic suppression using the open stubs," Microwave and Opt. Technology Lett., vol. 50, no. 7, pp. 1763-1766, Jul. 2008.
  4. R. Mongia, I. Bahl, and P. Bhartia, RF and Microwave Coupled-line Circuits, Artech House, Inc, 1999.
  5. S. H. Choi, J. Y. Lee, K. B. Lee, and D. H. Shin, "Design of miniaturized symmetric microstrip DC Block," IEEE Proc. Asia-Pacific Microwave Conference, pp. 1-4, Dec. 2007.
  6. H. Zhu, Q. X. Chu, and X. K. Tian, "A UWB bandpass filter using slotline ring resonator with a notched band," Int. Conference on Microwave and Millimeter Wave Technol., vol. 5, pp. 1-4, May 2012.
  7. J. Oda, C. P. Chen, K. Kamata, T. Kato, N. Kato, T. Anada, and S. Takeda, "Design of wideband filters with high skirt-slectivity using improved parallel-coupled three-line units," IEEE Proc. Asia Pacific Microwave Conference, pp. 957-959, Nov. 2013.
  8. J. Ye, D. Qu, X. Zhong, and Y. Zhou, "Design of X-band bandpass filter using hairpin resonators and tapped feeding line," IEEE Symp. Computer Applications and Communications," pp. 93-95, Jul. 2014.