Pekka Eskelinen , Harri Eskelinen

A K-band microwave measuring system for the analysis of tree stems

Eskelinen P., Eskelinen H. (2000). A K-band microwave measuring system for the analysis of tree stems. Silva Fennica vol. 34 no. 1 article id 643. https://doi.org/10.14214/sf.643

Abstract

The internal structure of growing trees and freshly cut logs can be characterized in real time by analysing the transmission and reflection of Ku- or K-band microwave energy injected with a horizontal polarization towards the material. Information about the moisture content, material bends, number and location of knots and sections of spoiled wood e.g. due to insects can be gathered in real time. Most sensitive test parameters are attenuation, group delay and the rotation of a linearly polarized wavefront. A simultaneous recording of reflection reduces errors caused by non-significant surface deformations. The spatial resolution, humidity equalization and noise immunity can be improved by applying a wideband frequency modulation. Commercial building blocks supplemented with a special antenna arrangement give possibilities also for the rough harvester environment.

Keywords
microwave measurements; wood analysis; knot detection; stem quality evaluation

Received 9 July 1999 Accepted 7 February 2000 Published 31 December 2000

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