Signature Modeling 2017-2019: Final report

This work has been funded by the Swedish Armed Forces R&D programme for Sensors and low observables (FoT SoS, AT.9220419). This final report summarizes activities and results for the project Signature modeling during the years 2017-2019. The project has mainly focused on development and evaluation and by measurements to validate methods and methodology, physical models and modeling tools for signature modeling, both for the radar and EO/IR waveband regions. The objective was to calculate signatures for entire objects in natural background environments. This is necessary in order to deliver reliable signature data for more applied projects, like for example sensor assessment, target recognition studies and/or duel simulations in order to increase protection and/or sensor performance. On several occasions the project has delivered different types of platform signature data, both such available for measurements and validation and platforms with limited access. A significant part of the project had a more long-term ambition to increase competence and further develop methodology. The project has also followed the international development in the research area, participated at conferences as well as published results in scientific journals, and participated in national and international collaborations. Examples of main research activities within radar modeling is development and validation of radar cross-section calculation methods using so-called hybrid methods, where we within a rather extensive work have generated model data for a to-scale airplane model by the process of laser scanning and generation of a CAD model, followed by radar signature calculations. These calculations were validated by measurements of the radar cross-section on the airplane model at an outdoor measurement facility of FOI. We are also participating in the development of an electromagnetic calculation model for rough surfaces and inhomogeneous materials that give rise to scattered radiation, such as, e.g., clutter and composite materials. For the EO/IR region efforts was on developing signature modeling of a full platform, including flame or exhaust plume and its background. We have for example developed the methodology to go from a CAD model achieved by laser scanning of a full-size battle tank, to calculations of its IR signature and followed by field trial measurements for validation. Also, efforts was put on the development and implementation of a surface scattering model that takes into account the polarization and scattering properties (socalled BRDF), together with measurements of material properties of different kind of surfaces, in order to meet the growing threat from polarimetric sensors. Some examples of future improvement needs within the area of radar signature modeling are, e.g., to further improve the hybrid radar calculation methods of a full object with complicated structures, including a realistic background environment if necessary, including more advanced material surfaces and inhomogeneous materials. In the field of IR modeling, we need to continue our attention on validated modeling methods of exhaust plumes in addition to the main body signature, and the plume impingement on the hull and the near background environment. Additionally, we should also continue the work on specific material related signature effects, such as polarization, in order to meet new sensor threats.