Experiments on some particular permittivity sensors in nondestructive testing of dielettric materials

The basic principles of electromagnetic (EM) techniques for nondestructive testing (NDT) of dielectric materials are first reviewed in consideration of the physical phenomena involved in the interaction between the material being tested and the exploring radiation. Applications and experimental results of particular nondestructive measuring techniques based on the use of radio frequency (RF) capacitive and microwave (MW) resonant sensors are then reported. The aim is to investigate the possibility of using EM waves in industriai NDT of dielectric materials. The use of these waves for such purposes is not yet as common as that of other types of radiation and many aspects still require investigation.