A broad-band characterization method based on the junction of the full-wave analysis of a nonreciprocal strip transmission line with a predictive permeability tensor model is presented. The aim of this method is the direct measurement of the permeability tensor components spectra of magnetized thick samples, whatever their magnetization state is. The propagation constants of the dominant transverse electromagnetic (TEM) and higher order modes inside the measurement cell are obtained along with its scattering parameters (S-parameters). The apparition of magnetostatic modes and the nonreciprocal nature of the structure are probed. Procedures based on the use of this method to find accurate values of gyromagnetic resonance and the resonance line width DH are proposed. The direct analysis is validated by comparison of the calculated S-parameters with those obtained with an electromagnetic field simulator based on finite element methods (FEM).