A Method of Analysis of Symmetrical Four-Port Networks

An analysis of four-arm symmetrical networks such as a branched directional double stub coupler or the hybrid ring (rat race) is presented. The input wave is broken into an even and an odd mode and the vector amplitude out the various arms is computed from the sums or differences of the reflection o...

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Bibliographic Details
Published inI.R.E. transactions on microwave theory and techniques Vol. 4; no. 4; pp. 246 - 252
Main Authors Reed, J., Wheeler, G.J.
Format Journal Article
LanguageEnglish
Published 01.10.1956
Subjects
Arm
Bandwidth
Circuits
Couplings
Directional couplers
Frequency
Reflection
Signal analysis
Transmission line matrix methods
Voltage
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Summary:An analysis of four-arm symmetrical networks such as a branched directional double stub coupler or the hybrid ring (rat race) is presented. The input wave is broken into an even and an odd mode and the vector amplitude out the various arms is computed from the sums or differences of the reflection or transmission coefficients for the two modes. A zero decibel directional coupler is described and its possible use as a duplexer is proposed. The design of multiple stub directional couplers for any degree of coupling is discussed. A method of computing the bandwidth of all these couplers is outlined, and the bandwidth curves, the power out the various arms with respect to frequency of the zero decibel coupler, are computed. A tabulation is made for six different 3 db couplers (even-power split) and their standing wave ratio, evenness of power split and isolation of the fourth arm as a function of frequency assuming perfect performance at the band center.
ISSN:0097-2002
2331-088X
DOI:10.1109/TMTT.1956.1125071