作者: Wenlei Shan , Shengcai Shi , T. Matsunaga , M. Takizawa , A. Endo
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摘要: In this paper, we report on the design and experimental results of a fix-tuned Superconductor-Insulator-Superconductor (SIS) mixer for Atacama Large Millimeter/submillimeter Array (ALMA) band 8 (385-500 GHz) receivers. Nb-based SIS junctions current density 10 kA/cm/sup 2/ one micrometer size (fabricated with two-step lift-off process) are employed to accomplish ALMA receiver specification, which requires wide frequency coverage as well low noise temperature. Parallel-connected twin (PCTJ) designed resonate at center tune out junction geometric capacitance. A waveguide-microstrip probe is optimized have nearly frequency-independent impedance probe's feed point, thereby making it much easier match low-impedance PCTJ over band. addition, superconducting magnet fixed onto compact block provide efficient magnetic field coupling designed. The demonstrates minimum double-sideband temperature 108 K temperatures less than 167 whole (for an intermediate-frequency range 4-8 GHz).