Single-layer microstrip high-directivity coupled-line coupler with tight coupling

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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  • Yongle Wu
  • Yinliang Diao
  • Kwok-Hung Chan

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Original languageEnglish
Article number6407156
Pages (from-to)746-753
Journal / PublicationIEEE Transactions on Microwave Theory and Techniques
Issue number2
Online published8 Jan 2013
Publication statusPublished - Feb 2013


A novel symmetrical coupled-line circuit structure without patterned ground plane is proposed to design tight-coupling high-directivity couplers, which would be found in numerous applications in a microstrip RF front end because of its simple structure and inherent excellent compatibility. Based on a traditional even- and odd-mode technique, closed-form mathematical equations for both circuit electrical parameters and scattering parameters are obtained. Due to the use of two coupled-line sections placed in the vertical direction, the directivity of this novel coupler without any other compensation techniques can be enhanced while maintaining tight-coupling performance of almost 3 dB. For demonstrative purposes, three typical full-wave simulation examples with realized physical dimensions in microstrip technology are presented, indicating high directivity and tight coupling coefficient. Finally, a practical microstrip coupled-line coupler is designed and fabricated to operate at approximately 2 GHz. The measured results show good return loss, quadrature phase characteristics, high directivity, and strong coupling performances. © 1963-2012 IEEE.

Research Area(s)

  • Coupled line, high directivity, microstrip coupler, tight coupling

Citation Format(s)