Stability analysis of a time-domain MM code for electromagnetic scattering predictions

摘要

It is known that numerical electromagnetic scattering simulators based on a time-domain version of the mehtod of moments may exhibit instability phenomena induced by the joint space-time discretisation of the field equations. In this paper we address the above problem with specific reference to a simulation code which allows evalauting electromagnetic scattering from perfectly conducting bodies of arbitrary shape. The simulator relies on a triangular-patch geometrical model of the exterior surface of the scattering body and operates according to a marching-on-in-time technique, whereby the surface current distribution at a given time step is evalauted as a function of the previous distributions. A heuristic stability condition is devised for the simulator, which allows to define a proper time step, as well as a correct geometrical discretisation, ensuring convergence of the numerical procedure. The stability condition is discussed and validated by means of a few working examples.