We present a model that evaluates in the frequency domain the magnetic behavior of laminated SiFe alloys caused by a magnetic field imposed at the material edge. The model is based on plane wave theory describing how an electromagnetic wave penetrates a material. As the nonlinear material with hysteresis can cause harmonic frequency components of the field and induction inside the material, the model takes into account several harmonics simultaneously by applying the harmonic balance principle. The plane wave model is solved iteratively with a classical Preisach model as constitutive law. We compare the model with a time domain finite-element model and with measurements on a ring core and find a good correspondence. The CPU time is low if only a few harmonics are considered and if the nonlinearity of the material is rather mild.