Lens antenna

An antenna comprising two conductive plates, feeders distributed around the periphery of the plates, and a lens including a disc-shaped lens element positioned between the plates, said feeders being oriented to transmit and receive waves polarized in a direction forming an angle of less than 90.degree. with a major surface of the lens element, and said lens element having a radially-varying diffraction index in accordance with the Luneberg principle, wherein a portion of the distance between the two conductive plates is filled with a dielectric medium having a dielectric constant corresponding to that of air, and where the height of said dielectric medium varies relative to the height of the lens element, such that maximal equality is obtained between effective dielectric constants for a wave's E-field component which is parallel to the lens element major surface and the wave's E-field component which is perpendicular to the lens element major surface, at each point in the lens.