Focal region fields of distorted reflectors

The problem of the focal region fields scattered by an arbitrary surface reflector under uniform plane wave illumination is solved. The physical-optics (PO) approximation is used to calculate the current induced on the reflector. The surface of the reflector is described by a number of triangular domain-wise fifth-degree bivariate polynomials. A two-dimensional Gaussian quadrature is employed to numerically evaluate the integral expressions of the scattered fields. No Fresnel or Fraunhofer approximations are made. The relation of the focal fields problem to surface compensation techniques and other applications are mentioned. Several examples of distorted parabolic reflectors are presented and discussed.