Improved radiation characteristics of conical horns with plastics-foam lenses

The radiation characteristics of conical horns with plastics-foam lenses are studied. The use of a plastics-foam lens enables the aperture amplitude and phase to be controlled by changing the shape of the lens surface and the relative permittivity of the foam. Theoretical and experimental results for a conical-corrugated horn with double-refraction lens shows that uniform-transverse phase and amplitude distribution can be obtained, giving very high aperture efficiency with a relatively compact antenna.