Characteristic-based time-domain method for electromagnetic analysis

The characteristic-based time-domain method, developed in the computational fluid dynamics community (CFD) for solving the Euler equations, has been applied to solve electromagnetic problems. The characteristic-based algorithm has several advantages over other time-domain methods. First, it can suppress reflected waves from the truncated outer boundary by simply interdicting the incoming propagation from the split flux vectors. Second, the governing equation can be easily cast into a body-oriented curvilinear coordinates system, which greatly facilitates the computation of electromagnetic fields around a complex scatterer. In addition, the equations in flux vector form are split according to the sign of the eigenvalues. Forward differencing is adopted for the negative eigenvalues, and the backward one is used for the positive eigenvalues. This windward discretization enforces the directional propagation of information for wave motion, and hence provides a more robust stability than a central differencing scheme. In this paper, the characteristic-based finite-volume time-domain method is extended to two applications. One is the analysis of antenna radiation problem. The other is the scattering problem from conducting objects coated with lossy dielectric materials.