Compact Wide-Band and Narrow-Band Microstrip Bandpass Filters Using the LC Equivalent Model

Document Type : Research Article

Authors

Department of Electrical Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Khuzestan, Iran.

Abstract

This paper presents an improved design methodology for developing two types of microstrip bandpass filters, a narrowband filter and a wideband filter, employing stepped-impedance resonators (SIRs) and parallel stubs. The fundamental resonator integrates two parallel stubs and a centrally located air gap within a stepped-impedance structure. The corresponding even- and odd-mode capacitances are evaluated, and an additional SIR is coupled to the primary resonator to achieve the desired bandpass response through dimensional optimization. To verify the electromagnetic simulation results, an equivalent LC circuit model is extracted and analyzed, demonstrating strong agreement with the full-wave response. Owing to its compact geometry and structurally efficient configuration, the proposed filter is well suited for integrated microwave systems. The wideband implementation is designed to operate at a center frequency of 10.02 GHz, exhibiting an insertion loss of 1.03 dB, a return loss of 30.1 dB, and 1.33 GHz bandwidth. In contrast, the narrowband design achieves a center frequency of 2.4 GHz with an insertion loss of 0.15 dB, a return loss of 26.26 dB, and 102 MHz bandwidth.

Keywords

Main Subjects

References

[1]    J-Y Choi, J-S Ma, and W-S Kim, "Tunable High-Selectivity Wideband Bandpass Filter Using Triple-Mode Stub-Loaded Resonators Based on Liquid Crystals," Digital Object Identifier 10.1109/ACCESS, IEEE Access, vol. 13, p. 186090, November 2025, doi: 10.1109/ACCESS.2025.186090.
[2]    A. Bandyopadhyay, P. Sarkar, and R. Ghatak, “A bandwidth reconfigurable bandpass filter for ultrawideband and wideband applications,” IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS. II: Express Briefs, vol. 69, no. 6, pp. 2747–2751, 2022, doi: 10.1109/TCSII.2022.3167028
[3]    W. Luo, Z. Chen, Y. Zeng, L. Zhang, Y. Zhao, and C. Sun, "Design of Compact Dual-band Filter Based on Quarter Wavelength SIRs," 2022 International Applied Computational Electromagnetics Society Symposium (ACES-China), Xuzhou, China, 2022, pp. 1-3, doi: 10.1109/ACES-China56081.2022.10065035.
[4]    D. Tan, W. Yang, Z. Xu, and W. Yang, "Parameter Prediction of SIR Dual Band Bandpass Filter Based on Convolutional Neural Network," 2024 4th International Conference on Electronic Information Engineering and Computer Science (EIECS), Yanji, China, 2024, pp. 55-58, doi: 10.1109/EIECS63941.2024.10800526.
[5]    Sh. Khani, M. Danaie, P. Rezaei, and A. Shahzadi, "Compact Ultra-Wide Upper Stopband Microstrip Dual-Band BPF Using Tapered and Octagonal Loop Resonators " Frequenz, vol. 74, no. 1-2, 2020, pp. 61-71. https://doi.org/10.1515/freq-2019-0060
[6]    B. Mohammadi, A. Valizade, J. Nourinia, P. Rezaei, “Design of a compact dual-band-notch ultra-wideband bandpass filter based on wave cancellation method”, IET Microwaves, Antennas & Propagation, vol.9, pp. 1-9, 2015, https://doi.org/10.1049/iet-map.2014.0372
[7]    D.-J. Jung, J.-K. Lee, and K. Chang, “Wideband bandpass filter using microstrip ring,” Microwave and Optical Technology Letters, vol. 53, no. 1, pp. 154–155, Jan. 2011, doi: 10.1002/mop.25678
[8]    L. Guo, Z.-Y. Yu, and L. Zhang, “A dual-band band-pass filter using stepped impedance resonator,” Microwave and Optical Technology Letters, vol. 53, no. 1, pp. 123–125, Jan. 2011, doi: 10.1002/mop.25648
[9]    H. Miyake, S. Kitazawa, T. Ishizaki, T. Yamada, and Y. Nagatomi, “A miniaturized monolithic dual band filter using ceramic lamination technique for dual mode portable telephone,” in 1997 IEEE MTT-S Int. Microwave Symp. Dig., Denver, CO, USA, Jun. 1997, pp. 789–792, doi: 10.1109/MWSYM.1997.602908
[10]     L.-C. Tsai and C.-W. Hsue, “Dual-band bandpass filters using equal-length coupled-serial-shunted line and Z-transform technique,” IEEE Trans. Microwave Theory Tech., vol. 52, no. 4, pp. 1111–1117, Apr. 2004, doi: 10.1109/TMTT.2004.825680
[11]     N. Khajavi, S. V. Al-Din Makki, and S. Majidifar, “Design of high-performance microstrip dual-band bandpass filter,” Radioengineering, vol. 24, no. 1, pp. 32–37, Apr. 2015, doi: 10.13164/re.2015.0032
[12]     H. Zhu and A. M. Abbosh, “Single and dual band bandpass filters using coupled stepped impedance resonators with embedded coupled lines,” IEEE Microwave and Wireless Components Letters, vol. 26, no. 9, pp. 675–677, Sept. 2016, doi: 10.1109/LMWC.2016.2597180
[13]     F.-C. Chen, J.-M. Qiu, S.-W. Wong, and Q.-X. Chu, “Dual band coaxial cavity bandpass filter with helical feeding structure and mixed coupling,” IEEE Microwave and Wireless Components Letters, vol. 25, no. 1, pp. 31–33, Jan. 2015, doi: 10.1109/LMWC.2014.2369965
[14]    X. Wu, F. Wan, and J. Ge, “Stub-loaded theory and its application to balanced dual band bandpass filter design,” IEEE Microwave and    Wireless Components Letters, vol. 26, no. 4, pp. 231–233, Apr. 2016, doi: 10.1109/LMWC.2016.2537045
[15]    P. Velez, J. Bonache, and F. Martín, “Dual band balanced bandpass filter with common mode suppression based on electrically small planar resonators,” IEEE Microwave and Wireless Components Letters, vol. 26, no. 1, pp. 16–18, Jan. 2016, doi: 10.1109/LMWC.2015.2505636
[16]    D. Li, J. A. Wang, Y. Liu, Z. Chen, and L. Yang, “Selectivity enhancement technique for parallel coupled SIR-based dual-band bandpass filter,” Microwave and Optical Technology Letters, vol. 63, no. 3, pp. 787–792, 2021, doi: 10.1002/mop.32672.
[17]    P. N. Choubey and W. Hong, “Dual band bandpass filter designed by exploiting the second-order degenerated modes of the SIW cavity,” in Proc. 2015 Asia Pacific Microwave Conf. (APMC), Nanjing, China, 2015, pp. 1–3, doi: 10.1109/APMC.2015.7411657.
[18]    J. Xu, K. D. Xu, M. Zhang, and Q. Chen, “Dual band bandpass filter using two simples coupled microstrip rings,” Engineering Reports, vol. 3, no. 2, p. e12288, Sept. 2020, doi: 10.1002/eng2.12288.
[19]    J.-S. Hong and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications. New York, NY, USA: John Wiley & Sons, 2001, ISBN: 978 0471388777.
[20]    K. Hashimoto, M. Ueda, O. Kawachi, H. Ohmori, O. Ikata, H. Uchishiba, T. Nishihara, and Y. Satoh, “Development of ladder-type SAW RF filter with high shape factor,” in Proc. IEEE Ultrason. Symp. Int. Symp., vol. 1, Nov. 1995, pp. 113–116.
[21]    J. Torrecilla, C. Marcos, V. Urruchi, J. M. Sánchez Pena, and O. Chojnowska, “Liquid crystal dual mode band pass filter with improved performance,” Opto Electronics Review, vol. 23, no. 2, pp. 121–125, Jun. 2015, doi: 10.1515/oere 2015 0020
[22]    Y. Liu, D. Jiang, W. Cao, T. Yang, L. Xia, and R. Xu, “Microwave tunable split ring resonator bandpass filter using nematic liquid crystal materials,” ELSEVIER-Optik, vol. 127, no. 21, pp. 10216–10222, Nov. 2016, doi: 10.1016/j.ijleo.2016.08.034
[23]    X.-K. Bi, X. Zhang, S.-W. Wong, S.-H. Guo, and T. Yuan, “Synthesis design of Chebyshev wideband band pass filters with independently reconfigurable lower passband edge,” IEEE Trans. Circuits Syst. II: Express Briefs, vol. 67, no. 12, pp. 2948–2952, Dec. 2020, doi: 10.1109/TCSII.2020.3023459
[24]    M. A. Sánchez Soriano and C. Quendo, “Systematic design of wideband bandpass filters based on short circuited stubs and λ/2 transmission lines,” IEEE Microwave and Wireless Components Letters, vol. 31, no. 7, pp. 849–852, Jul. 2021, doi: 10.1109/LMWC.2021.3076924
[25]    J. Y. Choi, J. S. Ma, H. Oh, and W. S. Kim, “A reconfigurable narrow band bandpass filter using electrically coupled open loop resonators based on liquid crystals,” J. Phys. D: Appl. Phys., vol. 46, no. 46, p. 465307, 2024, doi: 10.1088/1361 6463/ad6dd0
[26]    H. Nimehvari Varcheh, P. Rezaei, and S. Kiani, "A modified Jerusalem microstrip filter and its complementary for low phase noise X-band oscillator," International Journal of Microwave and Wireless Technologies, Vol. 15, pp. 1707–1716, Dec. 2023, doi: 10.1017/S1759078723000703.
Journal of Modeling and Simulation in Electrical and Electronics Engineering
Volume 6, Issue 3 - Serial Number 25
In Progree
September 2026
Pages 1-8

Files

History

  • Receive Date: 05 February 2026
  • Revise Date: 26 February 2026
  • Accept Date: 21 April 2026

Share

How to cite

Statistics