We have developed, manufactured, and tested a waveguide mixer in the range 211–275 GHz on the basis of the superconductor–insulator–superconductor (SIS) tunnel structures. The methods of manufacturing high-quality tunnel structures on quartz substrates have been worked out. To extend the receiver band, the Nb/AlOx/Nb and Nb/AlN/NbN tunnel junctions with a high current density of up to 20 kA/cm2 are employed. The dependence of the characteristics of the receiving elements on the signal frequency is simulated for the intermediate-frequency band 4–12 GHz. The measurements demonstrate a good agreement of the input band of the receiving structures with the calculated results. The uncorrected noise temperature of the receiver amounts to 24 K at a frequency of 265 GHz, which is only two times higher than the quantum limit. The receivers under development are intended for a number of newly-built ground-based radio telescopes (“Suffa” and LLAMA), as well as for the “Millimetron” space program.

中文翻译：

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用于新射电天文项目的低噪声 Sis 接收器

我们基于超导体-绝缘体-超导体 (SIS) 隧道结构开发、制造和测试了 211-275 GHz 范围内的波导混频器。已经研究出在石英衬底上制造高质量隧道结构的方法。为了扩展接收器频带，采用了具有高达 20 kA/cm2 的高电流密度的 Nb/AlOx/Nb 和 Nb/AlN/NbN 隧道结。针对 4–12 GHz 中频频段，模拟了接收元件特性对信号频率的依赖性。测量结果表明接收结构的输入频带与计算结果非常吻合。接收器的未校正噪声温度在 265 GHz 频率下达到 24 K，仅比量子极限高两倍。