A novel method for extraction of dispersive dielectric parameters to 50 GHz is proposed. The method doesn’t require advanced de-embedding, and is based on correlation of measured and simulated generalized modal S-parameters of a line segment. First, VNA measurements for two line segments are made and used to compute generalized S-parameters of a difference segment. Second, 3D full-wave model of the difference segment with conductor model with roughness is used to identify the dielectric properties. We finalize the paper with the derivation of dielectric models for low-cost FR4-type and for expensive low-loss high-frequency materials. The advanced models can be used for practical electromagnetic analysis of interconnects for the 6-100 Gb/s realm.