Mode analysis of nonreciprocal metamaterials using a combination of field theory and transmission line model

A new approach to describe transmission characteristics of nonreciprocal metamaterial structures is proposed by using a combination of field theory and transmission line model. This approach is implemented into the analysis of nonreciprocal negative-epsilon transmission line that is composed of a normally magnetized ferrite-rod-embedded microstrip line periodically loaded with shunt inductive stubs. It is confirmed that the proposed approach can describe not only epsilon-negative characteristics below the cutoff, but also the nonreciprocal phase characteristics, and agrees well with numerical simulation results by finite element method.