The influence factors of wood Dielectric Constant

Dielectric constants of Larix gmelinii were measured at 1.1 MHz to 25 MHz (near to frequency of high-frequency heating), from oven-drying condition to 100% moisture content, with longitudinal, radial and tangential directions measuring in the experiment. The results showed that: the relationship between MC and dielectric constant can be described as exponential relationship from MC=8% to the fiber saturation point (FSP), above FSP it is linear relationship. The dielectric constant showed decreasing trends when frequency raised. When f> 10MHz change trend is slow. Permittivity across longitudinal direction is bigger than that across transverse direction, but the difference across tangential direction and that across radial direction is small.