Extraction of Dispersive Material Parameters Using Vector Network Analyzers and Genetic Algorithms

A novel method to extract dispersive properties for dielectrics over a wide frequency range is proposed. This method is based on measuring scattering parameters for planar transmission lines and applying genetic algorithms. The scattering parameters are converted into ABCD matrix parameters. The complex propagation constant of the TEM wave inside the line is obtained from A-parameters of the ABCD matrix. For planar transmission lines, analytical or empirical formulas for dielectric loss, conductor loss, and phase constant are known. The genetic algorithm is then used to extract the Debye parameters for the dielectric substrates. FDTD modeling is used to verify the dispersive parameter extraction by comparing with the measurement