Broadband permeability measurement method for ferrites at any magnetization state: Direct problem

A data processing program based on a full-wave electromagnetic (EM) analysis of a non-reciprocal transmission line partially filled with a ferrite sample is presented. A predictive permeability tensor model is introduced in the Maxwell equations to allow the program to work at any magnetization state. The dispersion diagram for the first significant modes inside the ferrite loaded region of the line is obtained. The presence of magnetostatic modes generated by magnetized ferrite inside the line is verified. Using a mode matching technique, the theoretical scattering parameters (S-parameters) of the non-reciprocal transmission line are calculated. The analysis is validated by the comparison between the calculated S-parameters with those obtained with a FEM based EM simulator and the measurements at limit cases.