The manufacture and geometric optics optimization of a double-curved broadband reflector antenna

A numerical model was developed for a double curved antenna sensitive to signals in the 1-5 GHz range. The two distinct orthogonal linear polarizations of the antenna were achieved using a broadband, pyramid shaped log-period primary feed. Expressions are presented for predicting the patterns and phase characteristics of the feed horn at different frequencies. The design effort included separate descriptions of the center of the antenna, which emits elevation diffraction patterns, and the transverse sections, which emit the azimuthal patterns. A geometric optics approach (Dunbar's method) was applied to optimize the central fiber spacing and the flat curves of the transverse sections. Measurements made of the radiation patterns, isotropic gain and output power of a prototype antenna were closely predicted with the model.