Industrial Research Limited

New Zealand Forest Research Institute Limited

Industrial Research Institute Limited

Stephen Geoffrey Riley

Wayne Stephen Holmes

Richard B Keam

A generator () directs microwave signals to a waveguide () having a linear array of slots (), and the signals are received by measuring device (). The local permittivity or moisture content of material adjacent the waveguide (), such as a stack of timber, may be determined at each slot () via regression analysis. The total permittivity or moisture may be determined by averaging measurements obtained for both transmission directions of the waveguide (). The apparatus may be used for controlling drying parameters, such as drying time, for the material.

Microwave moisture sensing via waveguide with slot array

This invention provides a method and apparatus for the sensing of moisture using microwave technology. The apparatus provides a wave guide having a linear array of slots in its broadwall. A detector detects reflected energy of microwave signals over a frequency range once the material is positioned over the slots. A value indicative of the power spectral density of the reflected signals is computed and a value for the moisture content of the material determined from the value of power spectral density. The slots are at an angle with respect to the longitudinal axis of the wave guide and the angle can be varied according to the material being tested.

Growing community of inventors

Rotorua, New Zealand

Stephen Geoffrey Riley