An hybrid formulation combining FDTD and TDPO

The finite difference time domain (FDTD) technique has been proven to be particularly well suited to study microwave circuits and antennas. However, its main limitation results from the increase in both computation time and memory storage when the studied structures become larger. On the other hand, asymptotic approaches, such as the physical optics are generally used to account for very large scatterers but are not valid to study small radiating structures. Several examples have been reported, in which a rigorous electromagnetic method was combined with an asymptotic approach in order to study small radiating sources close to large scatterers. So-called hybrid methods have been demonstrated as able to account for the environment of the antenna while maintaining the needed accuracy in the description of the antenna itself. This paper proposes a new hybrid technique that combines FDTD with the time domain physical optics (TPDO). As the whole approach is performed in the time domain, it is expected to be suitable for broadband analysis. Moreover, the physical optics allows the closeness between the small element and the large scatterer contrary to geometrical optics where the source is supposed to be far from the obstacle. Their support may even be the same but edge diffraction phenomena are not modeled.