Conductivity, at microwave frequencies

Unfortunately, there are few direct measurements of the complex conductivity at microwave frequencies, thereby avoiding the need for extrapolation from higher frequency data. Martens et al. (2001) present data in the range 8-600 GHz for PPy and PAni that can be described by the Drude model. However, the plasma frequencies are 7 meV, much lower than the 1 eV calculated from the known carrier density. This indicates that most carriers are localised by the disorder in the samples and that the density of delocalised states at the Fermi level is low. Prigodin and Epstein (2003) note that the low frequency response is provided by a very small fraction of the carriers that are highly mobile and have long scattering times. They develop a model for this... 

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