Near-field distribution of a paraboloidal reflector

A major problem in communication antenna design is to obtain maximum gain and efficiency from large reflector antennas; few paraboloidal or dish antennas have efficiencies greater than 70 percent. The basic problem is the spreading of power by the source feed located at or near the focus of the reflector, which causes a concentration of power near the center of the aperture. In order to determine what kind of field distribution is required in the feed region to produce a uniform distribution over the reflector the authors have studied the inverse problem of a plane wave incident normally upon a paraboloidal reflector