Simulation of radar signatures of arbitrary airborne targets

Accurate electromagnetic (EM) simulation of scattering of airborne targets is a challenging task. A large variety of simulation approaches and objects have been studied in literature, using both measurements and simulation. This contribution will describe the EM simulation capabilities at the Department Antenna Technology and Electromagnetic Modelling AEM of Fraunhofer FHR, including both full-wave (based on the Method of Moments MoM) and high-frequency techniques (based on ray tracing and Physical Optics) which are developed at FHR. Full-wave methods generally provide a numerically exact solution of Maxwells equations but may require immense simulation resources (simulation time and memory) for large objects or high frequencies. Contrary, ray tracing approaches are well adapted to high frequency simulations, where the dimensions of the relevant objects are larger than the wavelength. Additionally, hybrid methods aim at combining the benefits of different methods in order to provide even more efficiency for the computations. Both full-wave and high-frequency simulation approaches can handle metallic as well as dielectric materials and are currently used in a variety of simulation projects, including signature prediction of airborne targets, modelling of wind turbine scenarios and simulation of antennas on platforms. The simulation examples show that the tools developed at FHR are able to handle very complex scenarios and that the scattering of arbitrary targets is modelled efficiently and accurately. Typical results of the EM simulations are monostatic and b istatic RCS studies, calculation of High Resolution Range Profiles (HRRP), distribution of scattering centers (e.g. for low observability/stealth measures), and prediction of embedded antenna characteristics. Recent developments within the simulation codes allow for the modelling of time-variant scenarios, e.g. rotating wind turbine blades, rotating jet engine blades, or objects moving along a straight trajectory. Finally, the presentation will give a brief overview of the activities in the NATO research task group SET-200, Electromagnetic scattering prediction of small complex aerial platforms for NCTI purposes and the contributions to this group by Fraunhofer FHR.