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在计算噪声系数或等效噪声温度时,利用本文中方便的列线图就消除了从分贝到功率比值的冗长变挣。当两个频率宽度B相同的部件级联时,其合成的噪声系数由下面已知的简单关系式给定: F_(12)=F_1+F_2-1/G_1 (1)式中F_1和F_2分别是部件1和2的噪声系数,G_1是部件1的增益,F_(12)是合成的噪声系数。当直接从式(1)确定F_(12)时,量F_1、F_2和G_1通常是以dB给出,而不是按功率比值。于是
In calculating the noise figure or equivalent noise temperature, using the convenient nomogram in this article eliminates the lengthy change from decibel to power ratio. When two components with the same frequency width B are cascaded, the resultant noise coefficient is given by the simple relation known as: F_ (12) = F_1 + F_2-1 / G_1 (1) where F_1 and F_2 are respectively Is the noise figure for parts 1 and 2, G_1 is the gain for part 1, and F_ (12) is the resultant noise figure. When F_ (12) is directly determined from Eq. (1), the quantities F_1, F_2 and G_1 are usually given in dB instead of the power ratio. then