Modified Getsinger´s model for accurate determination of effective permittivity dispersion in multilayered microstrip lines

Getsinger´s Longitudinal Section Electric model describing the propagation characteristics of a single layer microstrip line is modified to cater for `n´ layers. An accurate closed-form expression for two and three layered structures is presented and validated against full-wave numerical results. The computed effective permittivity for a randomly selected two and three layer dielectric microstrip line is presented. In the selected examples, for the modified Getsinger model, the dispersion of effective permittivity is within 2-3% relative error for two-layer and within 6-7% relative error for three-layer dielectric microstrip lines for frequency up to 50 GHz. In contrast, for the same structures, the relative errors in previously reported works are above 10% for two layers and above 15% for three-layer dielectric substrates.