The complete design of microstrip directional couplers using the synthesis technique

Abdullah Eroglu, Jay Kyoon Lee

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


A symmetrical microstrip directional coupler design using the synthesis technique without prior knowledge of the physical geometry of the directional coupler is analytically given. The introduced design method requires only the information of the port impedances, the coupling level, and the operational frequency. The analytical results are first validated by using a planar electromagnetic simulation tool and then experimentally verified. The error between the experimental and analytical results is found to be within 3% for the worst case. The design charts that give all the physical dimensions, including the length of the directional coupler versus frequency and different coupling levels, are given for alumina, Teflon, RO4003, FR4, and RF-60, which are widely used in microwave applications. The complete design of symmetrical two-line microstrip directional couplers can be obtained for the first time using our results in this paper.

Original languageEnglish (US)
Pages (from-to)2756-2761
Number of pages6
JournalIEEE Transactions on Instrumentation and Measurement
Issue number12
StatePublished - 2008


  • Coupled lines
  • Directional couplers
  • Microstrip
  • Microwave
  • Synthesis
  • Two-line

ASJC Scopus subject areas

  • Instrumentation
  • Electrical and Electronic Engineering


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