A simple crack depth estimation method by using monostatic RCS

A simple depth estimation method for a crack on the metal surface has been proposed. This method is based on our finding that the back scattering from a crack causes periodical s (dips) as the frequency changes, and the first dip occurs when the depth of the crack becomes nearly one half of the incident wavelength. Dependencies of the crack´s aperture and the incident angle have also been studied from rigorous analysis, and considered as our depth estimation parameters. Test measurement has been made to check the accuracy of our estimation algorithm. It is found that the crack depth can be estimated within 3 percent error.