The paper aims the electromagnetic simulation of a synchronous impedance transformer using a combination of the finite difference time domain FDTD and the method of lines MoL. The study demonstrates that the hybrid technique called FDTD-MoL can be used for the characterization of passive microstrip circuits. The capability to combine different methods of electromagnetic simulation provides a powerful tool for interpreting the behavior of microwave circuits. The hybrid FDTD-MoL method can characterize microstrip planar structures and is comparable with previous case studies of electromagnetic simulation.