Spheroidal FDTD Method for Modeling 3-D Structures in Open and Closed Domains

A finite difference time domain (FDTD) method for analyzing spheroidal open and closed structures is introduced. Its mathematical equations are derived and discretized according to a designed geometrical model. The field´s singularities at the domain´s center and vertical axis are dealt with by deriving alternative field formulas. The method is then extended to open domains by deriving an absorbing boundary condition (ABC). The stability of the obtained model is determined by deriving its mathematical condition. Finally, the method is used to characterize spheroidal cavities and a conformal patch antenna.