Effects on microwave measurements and simulations when collecting data close to edges of wooden boards

Parameters like strength, moisture content, density and grain direction are important when sorting wood according to their individual properties. All those parameters can be correlated to microwave measurements of phase shift and attenuation. Measurements of phase shift and attenuation are, however, affected by the vicinity of a board edge. In this article a simulation of the measurement system is used to create a compensation function for the measurements taken close to edges as if those were taken where no effects of the board edge could be noticed. It is shown, by comparison with real measurements, that by doing this the deviation between the values measured close to the board edges and those measured in the middle of the board is decreased, meaning a higher accuracy can be achieved by using the compensating function.

► We model a microwave measurement system to increase the accuracy in the vicinity of an edge. ► Accurate measurements close to edges gives higher possibility to detect variations in small objects. ► Diffraction phenomena need to be taken into account when dielectric properties changes abruptly. ► Correlations can be done to measured data by using a model of the measurement system.