COMPLEX DIELECTRIC MEASUREMENTS AND ANALYSIS OF BRAIN-TISSUES IN THE RADIO AND MICROWAVE-FREQUENCIES

We present in-vitro complex dielectric measurements of gray and white matter of rat brains in the frequency range between 45 MHz and 26.5 GH z at body and room temperatures using the open-ended coaxial probe tec hnique with an HP8510B network analyzer, The measurement data exhibite d two separated dispersions, and were analyzed by means of a complex n onlinear least-squares technique, We suggest two empirical models to d escribe the experimental data: one containing two Cole-Cole functions was applied to the data from this paper, and another including one Hav riliak-Negami and one Cole-Cole function was utilized to a combination of past and present literature data in a wider frequency range from 1 00 kHz to 26.5 GHz, The adoption of previously published data at the f requencies below 45 MHz increases tile valid frequency range of the mo del.