Restricting the computational domain in FDTD-modeling of three-dimensional problems with axial symmetry

The paper considers the computation of non-stationary radiation in electrodynamic stuctures with circular symmetry using the finite-difference time-domain (FDTD) method. There is proposed a new kind of exactly absorbing boundary condition (ABC) at a spherical boundary which is usable in Cartesian coordinates. Realization and testing of this ABC were carried out in a problem of radiation of the axisymmetric pulse antenna fed by a coaxial cable.