Non-Destructive testing based on group delay calculation

The proposed work is dedicated to research on the behavior of planar metallic materials when subjected to electromagnetic near field field, in order to achieve a nondestructive characterization. The characterization system includes a vector network analyzer (VNA) and an evanescent microwave probe (EMP). The method is based on the measurement of reflection coefficient, the frequency shift, the phase delay and the group delay. The variations of these parameters give information about the probe-sample electromagnetic coupling, the sensitivity of the near field probe and about the state of sample under the test without altering its physical properties.