A general invariance of the ratio of open- and short-circuit impedances for linear n-port networks

A general invariance of the ratio of open- and short-circuit impedances for arbitrary linear n-port networks is presented. The invariance is derived in terms of the characteristic polynomials (describing the modes of oscillations) associated with an n-port network under various open- and short-circuit terminal constraints. The result is a generalization of the two-port invariance recently published by a number of authors.