%0 Research article
%T A K-band microwave measuring system for the analysis of tree stems
%A Eskelinen, Pekka
%A Eskelinen, Harri
%D 2000
%J Silva Fennica
%V 34
%N 1
%R doi:10.14214/sf.643
%U https://silvafennica.fi/article/643
%X 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.