Analysis of terahertz scattering from electrically large scatterer with NURBS modeling

A novel expression based on conventional Non-Uniform Rational B-Splines surfaces is proposed to model a scatterer, which can be used to overcome the deficiencies of conventional modeling method and can also be combined perfectly with the stationary phase method (SPM). Furthermore, we propose a fast and accurate algorithm to locate inner critical points and boundary critical points of physical optics (PO) integrals, as well as to locate stationary points of edge-diffracted integrals. The terahertz (THz) scattering field from an electrically large scatterer is evaluated by the physical theory of diffraction and SPM (PTD-SPM), which consists of four parts, including the PO scattering field from inner critical points, boundary critical points, corner points of PO integrals, and edge-diffracted field from the stationary points of edge-diffracted integral. Moreover, the order of magnitude of each part contribution is derived. Numerical results demonstrate that PTD-SPM is a valid and efficient algorithm for analyzing THz scattering from an electrically large scatterer.