Three-dimensional computation of reduction in Radar cross section using plasma shielding

We have performed three-dimensional (3-D) finite-difference time-domain (FDTD) simulations for calculating microwave scattering from metallic objects shielded by a plasma shroud. Such simulations are of interest for plasma-based stealth technology. The simulations yield a reasonable match with experimental measurements. A physical interpretation has also been provided for these results, in terms of the flow of electromagnetic power. Such an analysis is only possible using the detailed spatio-temporal evolution of electromagnetic fields that is provided by the FDTD method. We find that apart from absorption, the bending of waves toward regions of lower plasma density plays an important role in determining the extent of backscatter. This has major implications for plasma stealth applications, which have heretofore assumed that plasma absorption is the main mechanism. Also, bending could actually enhance radar scattering in directions oblique to the incident direction. We have also identified situations where 3-D simulations become necessary, and other situations where a composite one-dimensional simulation may be enough. This has practical relevance since it could help reduce the demand for computational resources while modeling large objects like aircraft.