Abstract
Electromagnetic waves are gradually used in wood inspection and treatment. Three important parameters need to be considered in the application of this method, including moisture content (MC), porosity, and dielectric constant (ε), which affect the effectiveness of the application of electromagnetic waves, and these parameters can interact with each other. This study’s objective is to elucidate the effect and mechanism of porosity on the ε of wood with different MCs (absolute dry to saturated) in the frequency(f) range of 1 Hz-107 Hz. The pore parameters of four wood species are obtained by mercury piezometer and optical microscope, and the ε of wood with different MCs is obtained by dielectric spectrometer. The results indicate that the effect of porosity on the ε of wood needs to consider both f and MC. Relationship between porosity and ε of absolute dry wood shows opposite patterns in different f bands. When f ≤ 200 Hz, the porosity is positively correlated with ε. When f > 200 Hz, the porosity is negatively correlated with ε. However, the effect of f on the ε with the increase of MC is complicated. When f is low, the correlation among MC, porosity and ε is not significant, and as the f increases, the relationship between MC and ε becomes linear, and the growth rate of ε is large for wood with small porosity. The results of this study provide a reference for use of ε to detect wood pore characteristics and MC.