To describe the propagation of volt

To describe the propagation of voltages and currents eigenstates in the N-TL system in Fig.2.5, from one MTL segment to another,an interface transfer matrix that couples the fields on these two adjacent MTLs needs to be considered. Ingeneral,MTLs can have internal coupling,i.e.,the perunit length MTL parametersL,C,Cc,and R,have off diagonal elements representing inductive or capacitive coupling between TLs. However for the sake of simplicity,we consider now an example of an MTL where TLs are uncoupled in each segment,i.e.,L,C,Cc,and R,are diagonal,and the coupling between modes is provided by the interface between adjacent segments as shown in Fig.2.5(a).We also assume that reactive coupling produced by evanescent fields that maybe excited at interface discontinuities in Fig.2.8 are approximately accounted for in the distributed TL parameters,since the TL segments are electrically short.This assumption has been verified by comparing MTL results to full wave simulations providing good accuracy.Accordingly,the interface coupling matrix modeling the“mode mixing”between two adjacent MTL segments,made of two TL each,is given by