Non-destructive evaluation of moisture content of wood material at GPR frequency

GPR wave's propagation is governed by the electromagnetic (EM) properties of a dielectric material as wood, which is affected by various material parameters such as moisture, as well as heterogeneities. This paper presents some laboratory measurements in the aim of studying the sensitivity of EM waves propagation properties to moisture variation and fibers direction in wood material. Dielectric relative permittivity was measured using resonance technique at 1.26 GHz (for Spruce and Pine wood samples) and compared with GPR measurements using 1.5 GHz dipole antennas for different moisture conditions. The results of this study show good relations between real/imaginary relative permittivity and moisture content of both wood samples. Moreover, due to the dependence of wood permittivity to moisture, GPR permittivity measurements in time domain present also good correlation with moisture content. (C) 2014 Elsevier Ltd. All rights reserved.