The design of miniature multilayer bandpass filters with mixed couplings

Shilong Qian*, Gerdus Brand, Jiasheng Hong, Petrie Meyer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


This paper introduces a new design process for miniature coupled resonator filters with mixed couplings, which can better preserve wideband response matching with coupling matrix prototype. A special type of matrix transformation is introduced in this paper to transform the coupling matrix into a configuration that consists of an equal number of capacitive and inductive main couplings. Based on this, lumped-element circuit models can be produced. Then, by using to transformations for some parts of the circuit, all the elements have realizable values. A miniature bandpass filter with a fractional bandwidth of 20% of this type based on N x N coupling matrix is demonstrated with both simulated and measured response. The filter is implemented using multilayer liquid crystal polymer circuit technology and has a compact size of 0.0294 lambda(g) x 0.0303 lambda(g) x 0.00052 lambda(g) where lambda(g) is the guided wavelength at the center frequency of 250 MHz.

Original languageEnglish
Pages (from-to)4072-4078
Number of pages7
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number12
Publication statusPublished - Dec 2013


  • Bandpass filters
  • coupling matrix
  • miniature filters
  • multilayer filters
  • wideband


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