Microwave Instrument for Accurate Moisture Measurement of Timber

In this report a new instrument developed for moisture measurement of timber is described. In order to determine the dependence of the dielectric properties of moisture many measurements of the properties of timber were performed at 10 GHz. The results showed that the attenuation through timber is dependent on moisture content, on density, and on temperature. In the developed instrument the attenuation of timber is measured at 10 GHz, the density is determined by ¿-ray attenuation and the temperature by an infrared detector. A microprocessor calculates the moisture content. Field tests have shown that the correlation coefficient between the moisture content determined by the instrument and measured directly is 0.993 and the standard deviation of the moisture per cent is 0.68.