Reconstruction of dispersive dielectric properties for PCB substrates using a genetic algorithm

Jianmin Zhang*, Marina Y. Koledintseva, James L. Drewniak, David J. Pommerenke, Richard E. DuBroff, Zhiping Yang, Wheling Cheng, Konstantin N. Rozanov, Giulio Antonini, Antonio Orlandi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)704-714
Number of pages11
JournalIEEE Transactions on Electromagnetic Compatibility
Issue number3 PART 2
Publication statusPublished - 10 Sept 2008
Externally publishedYes


  • Electromagnetic propagation in dispersive media
  • Finite-difference time-domain (FDTD) methods
  • Genetic algorithms (GAs)
  • Scattering parameters
  • Transmission lines

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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