Maximum sensitivity was required for the reception of Mariner V signals as it was occulted by the planet Venus. To meet this requirement, an ultra-low-noise radio-frequency system (ultra cone) was developed for the JPL/NASA Deep Space Instrumentation Facility (DSIF). The system consisted of an 85-foot antenna with a Cassegrain feed, low-noise transmission line components, and closed-cycle refrigerated maser amplifier. The antenna (at zenith), transmission line, and maser contributed about 9/spl deg/K, 2/spl deg/K, and 5/spl deg/K, respectively, for a total operating noise temperature of approximately 16/spl deg/K. The antenna feed, maser system, and calibration techniques are described in detail.
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Levy et al. (1968) studied this question.
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