Physical Realizability Criteria

The main objective of this paper is to present a brief survey of the theory of linear, passive, time-invariant n-ports both from an axiomatic standpoint and a synthesis point of view. hthe first approach the n-port is defined in terms of its behaviour in real-time and its steady-state behaviour is deduced as a logical consequence. In the second approach the network is restricted, apriori, to be of a special type, e. g. , lumped etc. and methods of realizing it in terms of a finite number of known building blocks are investigated, To the author's best knowledge no definitive study of the active n-port on either basis is available. However, under certain assumptions, an algebraic treatment appears to yield some non-trivial results. This method -will be applied to the synthesis of n-ports containing both positive and negative resistors. Several theorems concerning n-port stability are also given together with a discussion of nonreciprocity and its relation to gyrotropic media.