A novel broad-band chebyshev-response rat-race ring coupler

Chi-Yang Chang*, Chu Chen Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


A novel broad-band rat-race ring coupler with a unit element at each port and an ideal phase inverter at one of the ring arms is proposed and analyzed. Design equations based on Chebyshev equiripple functions are derived. The design curves of equal or unequal power division are also presented. Theoretical data show that the bandwidth of unequal power division with a specific return-loss value increases as the power division ratio increases or decreases from unity. For a 180° hybrid with equal power division (3 dB) and 15-dB return loss, the proposed rat-race ring may have a bandwidth of 4:1. Three circuits of this novel rat-race ring are realized using finite-groundplane coplanar waveguide. The measured results match very well with the theory.

Original languageEnglish
Pages (from-to)455-462
Number of pages8
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number4
StatePublished - 1 Dec 1999


  • Finite-ground plane coplanar waveguide
  • Phase inverter
  • Uniplanar ring coupler

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