Comparison of near-field millimeter wave probes for detecting corrosion pit under paint

Corrosion pitting defection is a critical issue in the maintenance of aircraft. Near-field microwave nondestructive techniques have been successfully used for defection of corrosion under paint. In this paper a comparison between several different millimeter wave probes is made for the detection and evaluation of corrosion precursor pitting under paint at Ka-band and V-band. Since the pittings investigated here are very small in size, spatial resolution and sensitivity of the probes are critical issues. If is shown that modified open-ended rectangular probes namely, tapered waveguide and dielectric slab-loaded waveguide probes provide high resolution and sensitivity for the detection and evaluation of very small pittings under paint.