Analysis of the BDF using Caustics of Parabolic Reflector Antennas

When designing contour beams by combining multiple beams, the antenna beam direction and feed position become very important. This relation between the beam direction and feed position is known as the beam deviation factor (BDF). Previously, an equation for the BDF was derived from an aperture phase distribution of a parabolic reflector antenna. In this paper, the BDF relation is estimated from the calculated results of caustics in the focal region of a reflector antenna. To obtain the caustics, focal region ray tracings are obtained for incident plane waves at various antenna parameters and incident angles. In particular, the differences between the caustics in the scanning and transverse planes are investigated. The obtained feed positions are compared with the previous BDF and electromagnetic simulation characteristics. Finally, the accuracy of the focal region ray tracings is ensured by comparing the BDF values obtained from both methods.