A. Ahlstrom Osakeyhtio

Kemira Oy

Pekka Jakkula

A method and apparatus for measuring the moisture content or dry content of either high or low loss materials having a moisture content in excess of 50% utilizing a dielectric waveguide in contact with the material to be measured. The waveguide may be either embedded into the wall of a process pipe or it may pass through the pipe. The length of the waveguide can be controlled by the addition of reflecting spikes. The waveguide is designed and the microwave frequency so chosen that the microwave signal is reflected at least ten times. The strength of the output microwave signal is a function of the moisture content.

Method and apparatus for measuring the moisture content or dry-matter

A method and an apparatus for detection of knots in lumber by means of microwave radiation. Radiation from a transmitter is directed toward a piece of lumber and the radiation reflected from and/or passed through the piece of lumber is detected by means of a receiver. A radiation field having a TEM wave mode is established on the surface of the piece of lumber by means of a transmitter, whereby a radiation field which includes a TM wave mode component is generated in a knot in the piece of lumber and this is detected by means of a receiver.

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Helsinki, Finland

Pekka Jakkula