Passive Inter Modulationfor Corrosion Assessment and Localization (PIMCAL)

It is well documented that corrosion, and many other non-perfections of metal structures, when exposed to multi-tone radio-frequency (RF) emissions exhibit Passive Inter Modulation (PIM) emissions. PIM establishes fundamental limits of performance for wireless sensor, communication, radar, and navigation systems that operate in high output power environments. Compounding the PIM problem is the large number of co-located RF and Microwave systems in typical military and commercial environments. When a signal with a least two frequencies or modulation is applied to a structure, additional frequency components will form at integer multiples of the separation frequency(s) between the signal components. Generally PIM processes have a signature based on the physical process that generates them. PIM is a very small effect, and its use in standoff detection and characterization of corrosion poses significant challenges with regard to receiver dynamic range, receiver sensitivity, linearity, accessible spectrum (unlicensed band use only preferred), and transmit power.(Approved for Public Release 15-MDA-8482 (17 November 15))