Validation method for numerical simulations of large objects using the T-matrix for a collection of scatterers

This paper presents a validation method for large-scale electromagnetic scattering simulation problems, especially such performed using the Finite-Difference Time-Domain (FDTD) method. Large computational volumes imply that the results suffer from numerical dispersion. In order to validate the simulation results for large geometries a T-matrix solution for a collection of spheres can be used. In this paper the solution has been restriced to two spheres separated along the z-axis. Monostatic and bistatic scattering results using FDTD and the T-matrix method are compared. It is concluded that the grid resolution in FDTD must be adjusted in order to maintain the accuracy if the size of the computational volume increases substantially.