Evaluation of the characteristic impedance of microstrip interconnect lines on printed-circuit-boards

Available numerical methods for the characterization of microstrip lines involve extensive computations. The question that rises is which method should be used for a particular case. We propose to evaluate the results given by these formulas. The geometrical parameters of the microstrip structure are chosen in the commonly used range for PCBs. The purpose is to find out if well worth the effort to significantly increase the computational complexity to determine the characteristic impedance. For this, we have applied all the formulas for the same set of parameters, and we have analyzed the results by comparing them with the ones given by finite-difference time-domain (FDTD) simulation.