Microwave detection of surface and volume moisture in building walls and related structures

Microwave technique for non-contacting volume and surface moisture measurements in concrete and building walls is described. The reflection and attenuation coefficients of an electromagnetic wave, in the microwave spectrum region, impinging upon a humid wall are studied. Reflection and attenuation are related to the water content. The attenuation coefficient is related to the space-average humidity, while reflection measurements depend also on the humidity profile. By means of a computer simulation surface humidity and surface humidity gradient are both measured by reflectometric techniques. Combining reflection and attenuation measurements, information about the humidity profile is obtained in a non-contacting way. Experimental results on reflection and attenuation measurements are also presented.