Balanced-To-Balanced Microstrip Diplexer Based on Magnetically Coupled Resonators

Armando Fernandez-Prieto, Aintzane Lujambio, Jesus Martel, Francisco Medina, Ferran Martin, Rafael R. Boix

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)


© 2013 IEEE. Two balanced-To-balanced planar diplexers based on magnetically coupled microstrip resonators are proposed in this paper. For the first prototype, each channel/differential-output is composed of a second order single-band balanced bandpass filter based on open-loop resonators. For the second diplexer example, the filters composing the differential outputs are fourth order and are implemented by means of folded stepped-impedance resonators. The design procedure for the differential response is quite straightforward, since it is based on the use of the well-known external quality factor and coupling coefficients concepts. Common-mode is inherently rejected thanks to the benefits of magnetic coupling, which precludes common-mode transmission over a wide frequency range. The proposed structure also offers a high level of channel-To-channel isolation. To demonstrate the usefulness of the proposed idea, the two prototypes are simulated, fabricated, and measured. Good differential-mode and common-mode performance is observed in both examples. Simulations and measurements show good agreement.
Original languageEnglish
Pages (from-to)18536-18547
JournalIEEE Access
Publication statusPublished - 28 Mar 2018


  • Balanced-To-balanced diplexer
  • common-mode rejection
  • differential-mode
  • magnetic coupling
  • microstrip resonators


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