A Class of Quadrature Couplers Based on Transformer

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

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Original languageEnglish
Pages (from-to)785-797
Journal / PublicationIEEE Transactions on Microwave Theory and Techniques
Issue number3
Online published28 Jan 2016
Publication statusPublished - Mar 2016


A study of lumped transformer-based directional couplers is proposed by converting a conventional two-port transformer into a four-port directional coupler. The directional coupler of this kind is a backward coupler that consists of a ferrite-core transformer and four or five associated lumped reactive elements. Four different topologies of the coupler are proposed with four different reactive element arrangements, namely, ring topology, cross topology, H-shaped topology, and twisted topology. Analysis and design equations are presented. Four different circuits with different frequency responses are derived. Four 13.56-MHz couplers with these four different topologies are designed, fabricated, and measured. Wideband, compact, and backward wave coupling features are theoretically and experimentally confirmed.

Research Area(s)

  • Directional coupler, HF/VHF/UHF techniques, transformer