Frequency-domain formulation for nonlinear method of moments

In this paper a frequency domain formulation of the method of moments taking into account the presence of ferromagnetic materials is presented. By combining the electric field definition, Ohm's law and Lorentz gauge inside every volume element into which the system is subdivided, a linear algebraic system of integral equations is obtained. Considering the nonlinear constitutive equation H=H(B) and the magnetization M a nonlinear algebraic system of equations is obtained. The unknowns of these systems are the time Fourier transforms of magnetizations and conduction currents. The solution of these systems for a finite number of harmonics gives the frequency domain solution of the problem. The use of pulse functions as subsection bases allows a quick matrix set up especially when regular volume shapes are selected. Calculated results are compared with results obtained with other methods.