Enhanced Aircraft Non-Cooperative Target Recognition

Traditionally, airborne maritime surveillance and air-to-air radar systems have not exploited multiple polarization data. This is mainly due to the fact that most were previously only capable of supporting a single polarization. However, an increasing number of new generation radar systems are fully polarimetric. With the ability to measure and simulate fully polarimetric radar signature data, new opportunities exist to improve non-cooperative target recognition (NCTR) capabilities. These include enhancing traditional techniques such as high range resolution (HRR), inverse synthetic aperture radar (ISAR), micro-Doppler, and jet engine modulation (JEM).  The Navy wishes to apply these capabilities to characterize or classify electrically large, nonstable targets such as the Boeing 737-800 commercial airliner and the Chinese Xian H-6 bomber. In this example, both aircraft have similar dimensions, with the Boeing 737-800 having a wingspan of 113’ and length of 130’ while the Xian H-6 bomber has a wingspan of 108’ and length of 114’. However, each aircraft has distinct features. In particular, the H-6 has armament rails that could have missiles/bombs or fuel tanks attached to them. The engines on the H-6 are also closer to the fuselage than the 737-800. So, one would expect to see distinct radar signatures for the two aircraft.  Electro Magnetic Applications, Inc. (EMA) and Spann Consulting Services (SCS) propose an extensive simulation effort for the Phase I effort. This effort would include generation of fully polarimetric synthetic radar signature data for targets of interest to NAVAIR, including the Boeing 737-800 and the Xian H-6 bomber. Signature data will be generated over frequency bands of interest to NAVAIR, including UHF through X-band using the shooting and bouncing rays (SBR+) technique given its extensive validation history and advanced physics models for radar signature prediction of electrically large targets. The simulations will also consider CAD model fidelity to quantify the level of detail required in the CAD models for accurate predictions. Further, studies will be will performed to understand differences in signature data for slightly different versions of the aircraft. For example, the 737-800 and the 737-800 Max have slightly different dimensions and features and the Xian H-6 has different weapons configurations. Simulations may also be performed with full wave solvers for rotating/moving parts to address effects such as JEM since asymptotic techniques are typically not used for engine inlets and cavities. EMA and SCS will study the synthetic data to identify opportunities for improving NCTR techniques through distinct trends and behavior in fully polarimetric data over multiple radar frequency bands and over many aspect angles. The ideas that show the most promise for improving NCTR techniques will be implemented during the Phase II.