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本文叙述了一个为五大学射电天文台设计建造的低温超低噪声混频器。该混频器的新元件包括改进的波导、短路活塞,射频滤波器及中频匹配电路和偏压电路。它工作于75—120GHz频率范围,被用于该频段的冷却接收机中(15K)。在接收机中通过一可调环形滤波器使本振和混频器耦合,混频器后接频率范围为4.5～5GHz,噪声温度T_IF=24K的中频系统。在本振频率f_(LQ)=110GHz本振功率仅30μW条件下,测得接收机双通道噪声系数T_(recDSB)=140K。测试结果说明混频器噪声温度T_(m.DSB)∠60K。
This article describes a cryogenic ultra-low noise mixer designed and constructed for the Radio University Observatory of Five. The mixer’s new components include improved waveguides, short-circuit pistons, RF filters and IF matching circuits and bias circuits. It operates in the 75-120GHz frequency range and is used in cooling receivers for this band (15K). In the receiver through an adjustable loop filter to local oscillator and mixer, the mixer followed by the frequency range of 4.5 ~ 5GHz, the noise temperature T_IF = 24K IF system. The receiver dual-channel noise figure T_ (recDSB) = 140K is measured under the condition that the local oscillator frequency f_ (LQ) = 110GHz local oscillator power is only 30μW. Test results show that the mixer noise temperature T_ (m.DSB) ∠ 60K.