On the properties of lossless reciprocal 4-port circuits with reflection symmetry

An invariant for lossless reciprocal 4-port circuits with reflection symmetry is derived. It is shown that all these circuits can be transformed by external compensation into ideal 4-port circuits with perfect matching and isolation. The transmission coefficient and isolation ports are uniquely determined by the invariant. Furthermore, a design method for the external compensating circuits is described.<
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