Near-field millimeter wave non-contact measurement of step and gap mismatch in aircraft and automotive panels

In this paper the capabilities of near-field and non-contact millimeter wave measurements for the purpose of accurately determining step and gap dimensions between two painted aircraft panels is demonstrated. Millimeter wave reflectometer with a single and a dual-differential open-ended rectangular waveguide probes were used in this investigation. It was shown that the dual-differential probe provides higher sensitivity than the single probe. A combination of a dual-differential and a single probe may be used to uniquely determine the step and gap dimensions from a combined set of output information.