Distributed-element circuit: Difference between revisions

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An unusual application of a circulator is in a reflection amplifier, where the [[negative resistance]] of a [[Gunn diode]] is used to reflect back more power than it received. The circulator is used to direct the input and output power flows to separate ports.<ref>Roer, pp. 255–256</ref>

Passive circuits, both lumped and distributed, are nearly always [[Reciprocity (network theory)|reciprocal]]; however, circulators are an exception. There are several equivalent ways to define or represent reciprocity. A convenient one for circuits at microwave frequencies (where distributed element circuits are used) is in terms of their [[S-parameters]]. A reciprocal circuit will have an S-parameter matrix, [''S''], which is [[Symmetric matrix|symmetric]]. From the definition of a circulator, it is clear that this will not be the case,

:<math>[S] = \begin{pmatrix}