Design and Experimental Validation of a Compact 10 dB Microstrip Directional Coupler for 2.4 GHz Applications

Authors

  • Mehmet O. Kok Department of Electrical and Electronics Engineering Nevsehir Haci Bektas Veli University, Nevsehir 50300, Turkey
  • Fatih Kaburcuk Department of Electrical and Electronic Engineering Sivas University of Science and Technology, Sivas 58000, Turkey https://orcid.org/0000-0002-7527-3850
  • Atef Z. Elsherbeni Department of Electrical Engineering Colorado School of Mines, Golden 80401, USA

DOI:

https://doi.org/10.13052/2025.ACES.J.401207

Keywords:

Directional coupler, coupling factor, wireless communications

Abstract

This paper presents the design, simulation, fabrication, and measurement of a compact 10 dB microstrip directional coupler operating at 2.4 GHz and fabricated on a cost-effective FR-4 substrate. The design process integrates analytical even-odd mode impedance synthesis, circuit-level simulation using ADS LineCalc, and full-wave electromagnetic (EM) optimization to control coupling, isolation, and insertion loss with high fidelity. The measured coupling factor was −10.3 dB at 2.4 GHz, with isolation exceeding 18 dB and insertion loss below −0.65 dB. The simulation-to-measurement deviation was only 0.4 dB, indicating strong design-to-fabrication correlation. A reflection coefficient less than −20 dB confirms excellent impedance matching, while the single-layer, compact layout enables easy integration into wireless front ends, antenna feeding networks, and RF measurement systems. Compared with similar FR-4 based couplers in the literature, this proposed design achieves competitive electrical performance and demonstrates better simulation–measurement deviation, without requiring premium substrates, multilayer fabrication, or lumped-element compensation.

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Author Biographies

Mehmet O. Kok, Department of Electrical and Electronics Engineering Nevsehir Haci Bektas Veli University, Nevsehir 50300, Turkey

Mehmet O. Kok received M.Sc. and Ph.D. degrees in Electrical Engineering from Syracuse University, Syracuse, NY, USA, in 2012 and 2020, respectively. From 2015 to 2016, he was with Anaren Microwave, Inc., Syracuse, NY, as an RF Engineer. He served as an Electrical Engineer with PPC-Belden, Inc., Syracuse, NY, from 2017 to 2018, and as an RF Engineer with TTM Technologies, Syracuse, NY, from 2018 to 2020. He is currently working at the Department of Electrical and Electronics Engineering at Nevsehir Haci Bektas Veli University, Nevsehir, Turkey. His research interests include electromagnetics, wireless communications, and RF/microwave design.

Fatih Kaburcuk, Department of Electrical and Electronic Engineering Sivas University of Science and Technology, Sivas 58000, Turkey

Fatih Kaburcuk received M.Sc. and Ph.D. degrees in electrical engineering from Syracuse University, Syracuse, NY, USA, in 2011 and 2014, respectively. During his graduate studies, he was a Research Assistant with Syracuse University and PPC-Belden Inc., Liverpool, NY. In 2014, he was a Visiting Research Scholar with the Department of Electrical Engineering, Colorado School of Mines, Golden, CO. He joined Erzurum Technical University in 2015 and Sivas Cumhuriyet University in 2019. He was promoted to Associate Professor in 2020 and to Professor in 2025. In August 2024, he joined the Department of Electrical and Electronics Engineering, Sivas University of Science and Technology, Sivas, Turkiye, where he currently serves as Head of Department. Kaburcuk is an Associate Editor of Applied Computational Electromagnetics Society (ACES) Journal. His research interests include numerical methods in electromagnetics, biological effects of electromagnetic radiation, and finite-difference time-domain analysis of antennas and RF devices.

Atef Z. Elsherbeni, Department of Electrical Engineering Colorado School of Mines, Golden 80401, USA

Atef Z. Elsherbeni received two honor B.Sc. degrees in Electronics and Communications, in Applied Physics, and a M.Eng. degree in Electrical Engineering, all from Cairo University, Egypt, in 1976, 1979, and 1982, respectively, and a Ph.D. degree in Electrical Engineering from Manitoba University, Winnipeg, Manitoba, Canada, in 1987. He started his engineering career as a part time Software and System Design Engineer from March 1980 to December 1982 at the Automated Data System Center, Cairo, Egypt.  Dr. Elsherbeni joined the faculty at the University of Mississippi in 1987 as an Assistant Professor of Electrical Engineering.  He advanced to the ranks of Associate Professor and Professor in 1991 and 1997, respectively, and became the Associate Dean for Research and Graduate Programs from 2009 to 2013.  He then joined the EECS Department at Colorado School of Mines in August 2013 as the Dobelman Distinguished Professor. He was appointed the Interim Department Head for EECS department from 2015 to 2016 and became the EE Department Head from 2016 to 2018. He spent a sabbatical term in 1996 at the EE Department, University of California at Los Angeles (UCLA) and was a visiting Professor at Magdeburg University in Germany and at Tampere University of Technology in Finland during the summers of 2005 and 2007, respectively. In 2009 he was selected as Finland Distinguished Professor by the Academy of Finland and TEKES. Dr. Elsherbeni is the Editor-in-Chief for ACES Journal, a past Associate Editor to Radio Science Journal, a past Chair of the Engineering and Physics Division of Mississippi Academy of Science, a past Chair of Educational Activity Committee for IEEE Region 3 Section, and the general Chair for the 2014 APS-URSI Symposium, the president of ACES Society from 2013 to 2015, and the IEEE Antennas and Propagation Society (APS) Distinguished Lecturer for 2020-2023. Dr. Elsherbeni is a Fellow member of IEEE and ACES. He is the recipient of the2023 IEEE APS Harington-Mittra Award for his contribution to computational electromagnetics with hardware acceleration and the recipient of the 2025 Computational Electromagnetics Award from ACES society.

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Published

2025-12-30

How to Cite

[1]
M. O. . Kok, F. . Kaburcuk, and A. Z. . Elsherbeni, “Design and Experimental Validation of a Compact 10 dB Microstrip Directional Coupler for 2.4 GHz Applications”, ACES Journal, vol. 40, no. 12, pp. 1198–1205, Dec. 2025.

Issue

2025: Vol 40 Iss 12

Section

General Submission

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