Application of the time-domain differential solver to 2-D electromagnetic penetration problems

Time-dependent Maxwell´s equations in differential and conservation form are solved numerically, and field components are computed for scattering and penetration involving arbitrary 2-D objects using upwind computational fluid dynamics (CFD) based techniques. The Lax-Wendroff explicit scheme, which is second-order accurate in time and space, is used. The object and surrounding space are divided into a number of zones, and the Cartesian coordinate system is converted to local body-fitted coordinate systems in those zones, to handle more conveniently arbitrary geometry cross sections as well as to facilitate implementation of the boundary conditions. The method of characteristic subpath integration, better known as the Riemann solver in CFD, is then applied to the transformed Maxwell´s equations, yielding the solution for the field components in the time domain. Both steady-state and transient fields can be computed. A fast Fourier transform is used to obtain frequency-domain information. Both radar cross sections and near field distributions are presented for some canonical geometries