Apparatus for determining the water content of isotropic materials by means of microwave absorption

摘要

The principle of measurement is based on the microwave absorption by the water content of a sample. The sample is located in a closed single-reflection measurement cell which is fed by a microwave oscillator which is frequency-modulated within the absorbing frequency range of the sample. The sample partially or completely fills the end section of a circular or rectangular waveguide forming the measurement cell. The waveguide is sealed off with a short circuit plate so that two planar travelling waves with a homogeneous field distribution are present in the measurement cell.