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@Gary O'Neil, N3GO : 20 December 2019
/g/nanovna-users/message/8429

Dear Gary,

Thank you, very much indeed, because you noticed this !

Well, in our sow this means :

"keep the signal flow diagrams, use them to correctly express the
relations between a-s and b-s at joining ports, and forget the -most
disorientating- "rules" of them".

And we used it in this way for more than 25 years until last January
2019, when we found -with much pleasure, indeed- its full independent
justification at:

D. M. Kerns and R. W. Beatty, "Basic Theory of Wave guide Junctions and
Introductory Microwave Network Analysis" [*], Part 2, Introductory Microwave
Network Analysis, 2.18 Signal Flow Graph Applied to the Scattering Equations
pp.123-124, International Series of Monographs in Electromagnetic Waves,
Editors: A. L. Cullen, V. A. Fock J. R. Wait, Volume 13, Pergamon Press Inc,
First Edition, 1967:

"(f) Comments on use of signal ?ow graphs

This technique offers nothing fundamentally new and, if correctly applied, yields
the same results one would obtain by solutions of the scattering equations.
It seems to be simpler in some eases to write down the solutions by inspection of
diagrams rather than by algebraic manipulations. However, one must he careful
not to miss any of the loops, and this is a possible source of difficulty, especially
when we are dealing with 3-ports, 4-ports, or more complicated networks.

As a graphical aid to intuitive thinking about the analysis of systems, it is no doubt
valuable, and is therefore a tool to supplement conventional algebraic analysis."

Best regards,

gin&pez@arg

[*] 16 November 2019 : /g/nanovna-users/message/7092