A class of two-variable transfer functions and its application to the design of microwave filter networks

A novel approach to the design of microwave filter networks which consist of mixed, lumped, and distributed elements is presented from a two-variable point of view. This approach may be used to determine the delay time of transmission lines to be used and is illustrated using a class of double-resistive-terminated two-ports consisting of a cascade of two one-variable two-ports in different variables. This class is based on two Butterworth polynomials in different variables. Properties of two-variable transfer functions resulting in this class are given.