Inline Quasi-Elliptic Bandpass Filter Based on Metal 3-D Printing Technology

Jiayu Rao, Kenneth Nai, Jose Marques-Hueso, Povilas Vaitukaitis, Jiasheng Hong

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)
108 Downloads (Pure)


This article presents a novel waveguide loaded air slots' resonator (WLASR) comprised of a surrounding metal box and inserted metal disk with etched air slots. The proposed WLASR exhibits a comparable unloaded quality factor ( Qu ) to the coaxial resonator and allows controlling the electric and magnetic couplings separately. These attractive characteristics were first deployed to design a four-pole inline electrical-magnetic mixed-coupling bandpass filter centered at 2.82 GHz with a fractional bandwidth of 6.73% and two controllable transmission zeros (TZs) located at 2.65 and 2.98 GHz, respectively. Direct metal 3-D printing technology was utilized to manufacture the prototype. The measured results were auspicious for the first demonstrated 3-D printed prototype. Hence, two six-pole filters with multiple TZs, more compact sizes, higher Qu , and improved shape were designed. For experimental validation, one of them was printed with only two pieces. The measured results agreed well with the simulated ones.
Original languageEnglish
Pages (from-to)2156-2164
Number of pages9
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number4
Early online date1 Feb 2022
Publication statusPublished - Apr 2022


  • Bandpass filters (BPFs)
  • inline structure
  • metal 3-D printing
  • mixed coupling
  • transmission zeros (TZs)

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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