High isolation and compact diplexer using the hybrid resonators

Tao Yang*, Pei-Ling Chi, Tatsuo Itoh

*Corresponding author for this work

Research output: Contribution to journalArticle

127 Scopus citations


In this letter, a compact microstrip diplexer with very high output isolation is proposed. This diplexer consists of compact hybrid resonators, which are capable of introducing transmission zeros at desired frequencies and meanwhile suppressing signals below the resonant frequencies through tapping the feeding line close to the shorted vias. By designing the transmission zero of the lower-frequency channel in the higher passband, and utilizing the high lower-stopband suppression property of the higher-frequency channel, very high diplexer output isolation can be achieved. The proposed diplexer with center frequencies at 1.8 and 2.45 GHz, respectively, has demonstrated better than 55 dB output isolation and more than 55 dB suppressions in the stopbands. Furthermore, the diplexer occupies only a small area of 0.13λ0 × 0.2λ0.

Original languageEnglish
Article number5491067
Pages (from-to)551-553
Number of pages3
JournalIEEE Microwave and Wireless Components Letters
Issue number10
StatePublished - 1 Oct 2010


  • Compact diplexer
  • high isolation
  • high stopband suppression
  • hybrid resonator

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