Characterization of Transmission Lines on PCB from S-Parameters by Determining the Dielectric and Conductor Losses at the Crossover Frequency

Full characterization of transmission lines fabricated on printed circuit boards is presented in this paper. For this purpose, the frequency at which the attenuation curves associated with the conductor and dielectric losses cross over is first determined to exactly separate the corresponding contribution to the total attenuation. Afterward, permittivity, loss tangent, effective geometry, and rms roughness are obtained from the propagation constant and characteristic impedance data for allowing the transmission line representation up to 20 GHz. Using the extracted parameters, the excellent model-experiment correlation for the S-parameters of the lines is observed. In fact, the curves of complex-impedance versus frequency are also corrected from undesired resonances typically occurring in experimental data. Finally, it is demonstrated that the extracted parameters allow performing causal time-domain simulations.