Abstract: The invention relates to apparatus for converting electromagnetic waves with a particular polarization into waves having circular polarization wherein a single or multi-layer conductor grid structure is placed in front of the radiation aperture. If it is necessary due to spatial requirements of the radome, the circular polarization grid may be non-planar and according to the invention the geometric development of the grid structure can be determined by projecting a desired grid structure disposed in the radiation aperture plane upon a non-planar such as a cone-shaped surface. The manufacture of the grid structure can be accomplished by first forming the grid structure on a surface such as plastic with conducting strips or members formed thereon and so arranged such that when the plastic sheet is formed into a cone by removing a pie-shaped segment the desired non-planar pattern results.

Abstract: Apparatus for converting the polarization of electromagnetic waves from linear polarization to circular polarization wherein a plurality of layers of meandering electrical conductors are formed into a sandwich mounted one above the other wherein at least some of the conductors on different sandwich layers are in phase with each other but in which at least one of the electrical conductors on at least one of the sandwich layers are formed so that adjacent or some of the conductors are not in phase with each other but are phase offset such that the composite structure produces improved circular polarization as compared to polarization converters of the prior art. The sandwich structure according to the invention can be utilized as integrated into a radome of a tracking radar antenna for example.