A Comprehensive Review on Microstrip Couplers

Structure, Design Method and Performance

  • Abbas Rezaei Department of Electrical Engineering, Kermanshah University of Technology, Kermanshah, Iran http://orcid.org/0000-0003-0642-6726
  • Salah I. Yahya (1) Department of Communication and Computer Engineering, Cihan University-Erbil, Erbil, Kurdistan region – F.R. Iraq. (2) Department of Software Engineering, Faculty of Engineering, Koya University, Koya KOY45, Kurdistan region – F.R. Iraq https://orcid.org/0000-0002-2724-5118
  • Leila Nouri Faculty of Electrical, Electronic Engineering, Duy Tan University, Da Nang 550000, Vietnam http://orcid.org/0000-0003-0506-0478
Keywords: ABCD Matrix, Branch-line, Coupler, Directional, Microstrip


In this work, several types of microstrip couplers are investigated in terms of structure, performance and design methods. These planar 4-ports passive devices transmit a signal through two different channels. Designers' competition has always been in miniaturizing and improving performance of couplers. Some couplers have been offered with a novel structure, which is a special feature. A high-performance coupler should have high isolation and low losses at both channels. The channels are usually overlapped so that the common port return loss in these channels should be low. Among the couplers, those with balanced amplitude and phase are more popular. The popular mathematical analysis methods are even/odd mode analysis, extracting the information from the ABCD matrix and analyzing the equivalent LC circuit of a simple resonator. According to the phase shift value, couplers are classified as 90º and correct multiples of 90º, where a microstrip 0º coupler can be used as a power divider. Some couplers have filtering and harmonic elimination features that are superior to other couplers. However, few designers paid attention to suppressing the harmonics. If the operating frequency is set in according to the type of application, the coupler becomes particularly valuable.ABCD Matrix


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Author Biographies

Abbas Rezaei, Department of Electrical Engineering, Kermanshah University of Technology, Kermanshah, Iran

Abbas Rezaei is an Assistance Professor of Electrical Engineering in Kermanshah University of Technology. He
received the B.Sc., M.Sc. and Ph.D. in Electronics Engineering from Razi University, Kerman-shah, Iran, in 2005, 2009 and 2013, respectively. His current research interests include RF and microwave circuits, computational intelligence and nanotechnology.

Salah I. Yahya, (1) Department of Communication and Computer Engineering, Cihan University-Erbil, Erbil, Kurdistan region – F.R. Iraq. (2) Department of Software Engineering, Faculty of Engineering, Koya University, Koya KOY45, Kurdistan region – F.R. Iraq

Salah I. Yahya is a Professor, joined the Department of Software Engineering at Koya University in 2010. He has a B.Sc. degree in Electrical Engineering, M.Sc. degree in Electronics and Communication Engineering and Ph.D. degree in Communication and Microwave Engineering. He is a Consultant at the Iraqi Engineering Union. Dr. Yahya is a senior member of the IEEE-USA and a member of AMTA-USA, SDIWC-Hong Kong. His research interest include; Antenna, Microwaves, EMW propagation, Numerical Dosimetry, Microwave passive components design, ANN.

Leila Nouri, Faculty of Electrical, Electronic Engineering, Duy Tan University, Da Nang 550000, Vietnam

Leila Nouri is a staff member, with a Ph.D. degree, at the Faculty of Electrical - Electronic Engineering, Duy Tan University. She is also a researcher at the Institute of Research and Development, Duy Tan University, Da Nang, 550000, Viet Nam.


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How to Cite
Rezaei, A., Yahya, S. I. and Nouri, L. (2023) “A Comprehensive Review on Microstrip Couplers: Structure, Design Method and Performance”, ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY, 11(1), pp. 22-31. doi: 10.14500/aro.11108.
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