Fig. 10

Real (above) and imaginary (below) part of the permittivity of softwood vs moisture content from the literature: diamonds [26] at 0.9 GHz, circles [26] at 2.375 GHz and squares [27] at 1.26 GHz. Filled symbols for the E-field perpendicular to and open parallel to the wood fibers. The solid lines are isotropic equivalent permittivity, \(\varepsilon^{\prime}_{{\text{w}}}\) and \(\varepsilon^{\prime\prime}_{{\text{w}}}\), used in the modeling based on [26]. The dashed-dotted line is the higher value of \(\varepsilon^{\prime\prime}_{{\text{w}}}\) also used in the modeling