Large lateral feed displacements in a parabolic reflector

The radiation patterns of a parabolic reflector with large lateral-feed displacements are computed utilizing both the vector current method and scalar aperture theory, and compared to experimental results. The theory is general enough to include asymmetric primary pattern illumination. The scalar and vector solutions are derived from the same initial equation so that the approximations used in obtaining the scalar solution are clearly displayed. Results from the vector and scalar theories are compared and the range of validity of the approximate analysis is indicated.