A comparison of the properties of radiating boundary conditions in the FDTD method for finite discretisation and non-planar waves

The availability of effective radiating boundary conditions (RBCs) for use with the finite difference time domain (FDTD) method is essential for the efficient application of the technique to scattering and radiation problems. The majority of published analyses of the behaviour of various RBCs are restricted to the case of plane wave incidence and infinitely fine discretisation, situations which never occur in practice. In the present contribution, the behaviour of RBCs in realistic situations is presented and it is shown that the plane wave behaviour is not a good guide as to the behaviour in practical cases. The best RBC for use in general cases is discussed