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一、前言由于卫星通讯和远距离探测技术的迅速发展,低噪声接收系统大量被应用,所以,要求精密测试各种低噪声整机系统和低噪声部件的噪声性能。为此,我们建立了7.5厘米波段低温噪声标准及其校准系统。标准源工作频率约4015兆赫,采用液氮直接冷却方式,输出形式为BJ—48波导型。室温输出法兰上的资用噪声温度为液氮温度+0.66K,其准确度为±0.05 K。
I. INTRODUCTION Due to the rapid development of satellite communication and long-range detection technology, low-noise receiving systems are widely used. Therefore, the noise performance of various low-noise whole system and low-noise components needs to be precisely tested. To this end, we have established a 7.5 cm band cryogenic noise standard and its calibration system. Standard source operating frequency of about 4015 MHz, liquid nitrogen direct cooling mode, the output form of BJ-48 waveguide. The ambient noise temperature at the room temperature output flange is +0.66 K at liquid nitrogen temperature with an accuracy of ± 0.05 K.