Analog Integrated Circuits and Signal Processing

, Volume 98, Issue 2, pp 409–415 | Cite as

Design of a miniaturized microstrip diplexer using coupled lines and spiral structures for wireless and WiMAX applications

  • Abbas RezaeiEmail author
  • Leila Noori
  • Hossein Mohammadi


In this paper, a planar microstrip diplexer consisting of two resonators integrated by three coupled lines is presented. The proposed resonators are composed of coupled lines and microstrip spiral cells. The realized diplexer operates at 2.88 GHz for wireless and 3.29 GHz for WiMAX applications. To obtain a compact size, low insertion losses and tune the resonance frequencies a designing method is presented based on the analysis of scattering and Z parameters of the proposed resonator. The designed diplexer has a miniaturized size of 0.028 λ g 2 . Another advantage of the proposed structure is a significant improvement in the insertion losses at the both passbands so that they are 0.36 and 0.44 dB at 2.88 and 3.29 GHz respectively where the return losses at the both passbands are better than 23.7 dB. The designed diplexer is fabricated and measured. There is a good agreement between simulated and measured results, which validates the introduced methodology.


Diplexer Insertion loss Microstrip Miniaturization Return loss 


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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Electrical EngineeringKermanshah University of TechnologyKermanshahIran
  2. 2.KermanshahIran

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