Time-Domain Line-Integral Representations of Physical-Optics Scattered Fields

A time-domain (TD) line-integral (LI) representation of the physical-optics (PO) radiation integral is developed for the scattering from a perfectly conducting surface illuminated by an electric Hertzian dipole. The proposed LI representation, which is valid and singularity-free for all near-field observers, is derived directly in the TD by introducing dyad potentials. This TD representation can be further expressed in terms of geometric-optics and boundary-wave components of the scattering mechanisms, as in the conventional frequency-domain LI representations. Using the proposed LI representation, the computational complexity is reduced by an order of the scatterer's linear electric size, compared with the straightforward numerical quadrature of the PO surface integral. Simple and complicated numerical examples are presented to demonstrate the efficiency and accuracy of the proposed TD-LI algorithm.