On the Optimum Performance of Variable and Nonreciprocal Networks

Lossless, reciprocal transformations of two-state and nonreciprocal two-ports are discussed. (Two-state networks are networks whose parameters may be switched simultaneously between two different values.) The minimum loss of such networks for various applications are shown to depend upon a single characteristic number which is invariant under the transformations studied. When a two-state or nonreciprocal material is used to realize such a network, there is an upper limit for the value of the characteristic number, and this is defined as a figure of merit for the material.