This paper presents new ideas and methods for constructing the transfer function

solving the open-circuit impedance parameters

etc. The classical Darlington’s realization theory has been generalized to include arbitrary generator and load impedances （Non-Foster positive-real functions）. The previous researches on realization theory of reactance two-port networks are the special cases of this theory.From the theoretical point of view

the results presented in this paper are the general realization theory of reactance two-port networks. From the practical point of view

this theory extends greatly the range of applications.