Aperture efficiency enhancement in a Cassegrain system by means of a dielectric lens

We have succeeded in boosting the overall aperture efficiency of a Cassegrain radio antenna by introducing a dielectric lens into the beam. The gain amounts to 0.7 dB, or about 17%, at millimeter wavelengths. The lens, of weak optical power, but strongly aspherical figure, is placed a short distance in front of the feed. It serves to redistribute the field in the aperture of the telescope, making the amplitude more uniform, with a sharp cutoff at the edge. The aberrations (defocusing and spherical) introduced by the lens are balanced by slightly displacing the secondary mirror. The lens can be adapted to many existing telescopes employing classical paraboloid‐hyperboloid optics, at minimal expense.