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Aperture efficiency enhancement in a Cassegrain system by means of a dielectric lens
Author(s) -
Hudson Jerome A.,
Plambeck Richard,
Welch William J.
Publication year - 1987
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs022i006p01091
Subject(s) - cassegrain reflector , optics , lens (geology) , physics , aperture (computer memory) , focal length , paraboloid , cassegrain antenna , feed horn , telescope , millimeter , amplitude , parabolic reflector , antenna (radio) , radiation pattern , telecommunications , periscope antenna , computer science , mathematics , geometry , surface (topology) , acoustics
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.