Conical reflector antennas having very low cross-polarization levels

The use of a line source with conical reflector has been studied by M.S.A. Sanad et al. (see Canadian Journal of Elect. and Computer Engng., vol.15, no.1, p.15, 1990). Only one half of the cone was utilized and the cross-polarization level was very high. In the present work, two identical sets of that simulated line source are simultaneously used to illuminate both sides of the cone. The parabolic cylindrical surfaces act as subreflectors and together with the feed horns simulate a line source to illuminate the main reflector which is a conical surface. The subreflectors are designed such that their reflected rays are exactly received by the main reflector. The radiation pattern of the antenna is calculated using the extended aperture integration method, where both reflected and diffracted rays are included. Due to the symmetry of the system the geometrical optics cross-polar components on the aperture cancel each other and thus the geometrical optics cross-polarization is eliminated. The cross-polarization level due to edge diffraction is very low.<>