An effective method for extracting parameters of a Debye or a Lorentzian dispersive medium over a wideband frequency range using a genetic algorithm (GA) and a transmission-line model is presented. Scattering parameters (S-parameters) of the transmission-line sections, including a parallel plate, microstrip, and stripline, are measured. Wave equations for TEM/quasi-TEM mode with a complex propagation constant and a frequency-dependent wave impedance are used to evaluate the corresponding S-parameters in an analytical model. The discrepancy between the modeled and measured S-parameters is defined as the objective function in the GA. The GA is used for search of the dispersive-medium parameters by means of minimizing the objective function over the entire frequency range of interest. The reconstructed Debye or Lorentzian dispersive material parameters are corroborated by comparing the original measurements with the FDTD modeling results. The self-consistency of the proposed method is demonstrated by constructing different test structures with an identical material, i.e., material parameters of a substrate extracted from different transmission-line configurations. The port effects on the material parameter extraction are examined by using through-reflection-line calibration.
J. Zhang and M. Koledintseva and J. L. Drewniak and D. Pommerenke and R. E. DuBroff and Z. Yang and W. Cheng and K. Rozanov and A. Orlandi and G. Antonini, "Reconstruction of Dispersive Dielectric Properties for PCB Substrates Using a Genetic Algorithm," IEEE Transactions on Electromagnetic Compatibility, Institute of Electrical and Electronics Engineers (IEEE), Aug 2008.
The definitive version is available at http://dx.doi.org/10.1109/TEMC.2008.927923
Electrical and Computer Engineering
Keywords and Phrases
Electromagnetic Propagation in Dispersive Media; Finite-Difference Time-Domain (FDTD) Methods; Genetic Algorithms (GAs); Scattering Parameters; Transmission Lines
Article - Journal
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