Development of a Spherical Vacuum Window for Cryogenic Receiver

Vacuum window is a key part of a cryogenic receiver, which isolate the feed from the ambient environment. Traditional flat vacuum window leads to a metal flange over the aperture of the feed, which inevitably distorts the radiation pattern of the feed and degrades the performance of the reflector antenna. This paper presents a spherical vacuum window made of Polymethyl Methacrylate (PMMA), which minimizes the negative effects on performance. And the measured results matches reasonably well with the simulation.