Despite the fact that the dependence of the GMI on the geometry of the electrical conductor (ribbons, wires, multilayers meander-likes) and external parameters is somewhat complex, there are theoretical models that allow calculation of the GMI to within some approximations. Beside the dependence of the GMI on the frequency of the current there are other sources that contribute to the frequency dependence of the GMI, such as the motion of the domain wall and the ferromagnetic resonance.