Causal Model Implementation for the Conductor Surface Roughness Effect on the Attenuation and Delay of Microstrip Lines

The conductor surface roughness effect on microstrip lines is physically represented by proposing a step-by-step methodology that uses experimental
$S$
-parameters supported by electromagnetic (EM) simulations assuming smooth conductor surfaces. This avoids implementing the microstrip line model by arbitrarily fitting simulations with experimental data that include multiple-frequency-dependent effects. Furthermore, a priori knowledge of the roughness profile is not required in this proposal. From the analysis, the peak-to-valley feature of the surface roughness that allows for the representation of the corresponding effect on the electrical response of the lines is obtained. The implemented models show a correlation with experimental data up to 35 GHz.