A design of a dual-band bandpass filter based on modal analysis for modern communication systems

Ali Lalbakhsh, Seyed Morteza Alizadeh, Amirhossein Ghaderi, Alireza Golestanifar, Bahare Mohamadzade, Mohammad (Behdad) Jamshidi, Kaushik Mandal, Wahab Mohyuddin

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54 Citations (Scopus)
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A dual-band bandpass filter (BPF) composed of a coupling structure and a bent T-shaped resonator loaded by small L-shaped stubs is presented in this paper. The first band of the proposed BPF covers 4.6 to 10.6 GHz, showing 78.9% fractional bandwidth (FBW) at 7.6 GHz, and the second passband is cantered at 11.5 GHz with a FBW of 2.34%. The bent T-shaped resonator generates two transmission zeros (TZs) near the wide passband edges, which are used to tune the bandwidth of the first band, and the L-shaped stubs are used to create and control the narrow passband. The selectivity performance of the BPF is analyzed using the transfer function extracted from the lumped circuit model verified by a detailed even/odd mode analysis. The BPF presents a flat group delay (GD) of 0.45 ns and an insertion loss (IL) less than 0.6 dB in the wide passband and a 0.92 IL in the narrow passband. A prototype of the proposed BPF is fabricated and tested, showing very good agreement between the numerically predicted and measured results.
Original languageEnglish
Article number1770
Pages (from-to)1-13
Number of pages13
Issue number11
Publication statusPublished - Nov 2020

Bibliographical note

Copyright the Author(s) 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


  • dual-band BPF
  • tunable bandwidth
  • LC circuit
  • microstrip tech


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