Multi-component mixture modeling for the dielectric properties of rubber wood at microwave frequencies

Dielectric properties from 1 to 18 GHz of rubber wood are modeled using gen eralized mixture equations and also with equations proposed by Weiner, Kras zewski, Looyenga and Landou, Lichtenecker. Dielectric properties were measu red with an open-ended coaxial line-sensor in three structural directions l ongitudinal, radial and tangential and at different moisture contents. The dielectric constants were predicted well by the Weiner model for all struct ural grain directions and it was found that the degree of binding decreases with increasing frequency. However, the Weiner model cannot be used for pr edicting the dielectric loss factor at frequencies below 3 GHz. This may be due to the high conductive loss in this frequency region. The lower value of the exponents in generalized mixture equation was found suitable for fit ting the experimental data as well as the Kraszewski equation. Values predi cted by Lichtenecker equations are in well agreement with the experimental data at higher microwave frequencies. The prediction of dielectric loss fac tor using Kraszewski, Looyenga equations were not possible at frequencies b elow 3 GHz since it is dominated by conductive loss. Above 3 GHz, it was we ll predicted by Kraszewski and Looyenga equations.