Beam efficiency of large reflector antennas subject to correlated random surface errors

The beam efficiency of a large reflector antenna is characterized by its random surface errors and the antenna aperture distribution. An improved mathematical model is presented to handle two-dimensional surface errors with zero mean and a relatively short correlation length. Pattern degradations and beam efficiency decrease due to surface errors are illustrated in the results explicitly. It is shown that tighter surface tolerances are required when low sidelobe level is desired. The linear surface errors will cause not only pattern degradation but also main beam broadening. Beam efficiency decrease is sensitive to both uniform and linear surface errors, but has little dependence on the F/D ratio.<>