Abstract: In order to calculate the wide-angle scanning characteristics of the dual reflector antenna, a hybrid pattern analysis method for the antenna is presented. We combine the geometrical optics (GO) with the physical optics (PO) based on the Fourier-Bessel technique, and propose an effective hybrid secondary pattern analysis method. The simulated analysis results of the hybrid method are in good agreement with the results presented in the literature, which shows that the method is feasible and accurate. Finally, the hybrid method is used to analyze a side-fed offset Cassegrain(SFOC) antenna, and its radiation characteristics as well as its gain under wide-angle scanning are given. The calculated results show that the radiation patterns of the SFOC antenna have less distortion, its gain losses are small, and its sidelobe levels are better than -20dB in the wide-angle scanning region.

Key words: wide-angle scanning, dual-reflector antenna, radiation pattern, side-fed offset Cassegrain antenna