Circuit modeling of resonant modes in MMIC packages using time domain methods

An important task in numerical modeling using 3D-full wave simulators based on the finite element -, the finite difference time domain - or the transmission line matrix (TLM) method is the excitation of infinitesimal dipoles or arbitrary surface current densities. In the case of an infinitesimal dipole excitation the corresponding electromagnetic field is known as Green´s function. A method is proposed to excite electric and magnetic surface current densities within an inhomogeneous filled cavity using the TLM method to determine the Green´s functions in terms of impedance and admittance functions. It is shown how to deduce equivalent circuits for these impedance and admittance functions, which can be used in commercial circuit simulators.