OBJECTIVE: Develop polarimetric imaging techniques to significantly improve small maritime target detection and classification capabilities. DESCRIPTION: The move of naval operations into the littorals exposes our ships to the small boat terrorist threat. The first step in discerning the intention of any particular small boat is to classify and fingerprint it so it can be observed over an extended period of time. Currently, inverse synthetic aperture radar (ISAR) techniques are used for ship classification. Large ships tend to have a rich set of discernable features making classification relatively straightforward. However, small boats rarely have such a rich set of discernable features. Polarimetric techniques in synthetic aperture radar (SAR) over land have shown the potential for improved ship classification performance using SAR polarimetric techniques By leveraging the expanded feature set available from a combination of polarimetric SAR and ISAR, a significant improvement in small boat classification performance seems possible. The expanded feature set includes both hard-body scattering characteristics and distinctive wake characteristics. The major challenge facing the community is that our knowledge about polarimetric ISAR and SAR phenomenology of small boats is very limited, and this prevents one from knowing how to interpret and exploit the scattering information for classification or identify how the robustness of polarimatric features, improves small boat classification (<100 ft length). The targets of radar operation are the C- and X-bands. PHASE I: Determine the feasibility of using polarimetric imaging techniques to significantly improve small maritime target detection and classification capabilities. PHASE II: Demonstrate the technique using specific exploitable scattering characteristics to enable both fingerprinting and classification. Assess the robustness of the feature set as a function of radar band, resolution and viewing geometry. PHASE III: Mature the polarimetric fingerprinting and classification approaches for real-time implementation. Transition the algorithms into a suitable tactical airborne radar system for use in the Fleet. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The techniques may be used with commercial overhead sensors for surveillance of the activity of fishing vessels as a part of regulation within the Extended Economic Zone (EEZ).