  This paper proposes a theory for designing stable interconnection of linear
active multi-port networks at the ports. Such interconnections can lead to
unstable networks even if the original networks are stable with respect to
bounded port excitations. Hence such a theory is necessary for realising
interconnections of active multiport networks. Stabilization theory of linear
feedback systems using stable coprime factorizations of transfer functions has
been well known. This theory witnessed glorious developments in recent past
culminating into the $H_{\infty}$ approach to design of feedback systems.
However these important developments have seldom been utilized for network
interconnections due to the difficulty of realizing feedback signal flow graph
for multi-port networks with inputs and outputs as port sources and responses.
This paper resolves this problem by developing the stabilization theory
directly in terms of port connection description without formulation in terms
of signal flow graph of the implicit feedback connection. The stable port
interconnection results into an affine parametrized network function in which
the free parameter is itself a stable network function and describes all
stabilizing port compensations of a given network.
