Characteristics of the cross-polarized radiation of dielectric radio lenses

The aperture method is used to investigate the characteristics of the cross-polarized radiation of dielectric lens antennas. Two concepts developed in the combined asymptotic method for analyzing the vector patterns of antennas of optical type are utilized: an idealized feed and the synthesis of the cross-polarized field distribution on the basis of a known principal distribution. It is shown that the cross-polarization (CP) levels of dielectric lens antennas near the axis are higher than those of parabolic antennas for the same values of F/D and Delta. It is also shown that, as in the case of reflector antennas, the CP levels of dielectric lens antennas depend on F/D, mu/nu, and Delta. A feed with nu/mu = 0.34 is found to be optimal from the point of view of CP for a plane-convex lens, while an electric-dipole type feed is optimal for hyperbolic and elliptic lenses.