噪声系数测量中的损耗修正技术

为了得到DUT的真实噪声系数，必须对测量过程中出现的额外损耗进行修正。现有的噪声系数分析仪只能对DUT前后的损耗和它们的组合进行修正。但是当有损器件存在于校准过程中而其在测量过程中没有被包含在DUT之后时，也需要进行修正。该新情况和已有3种情况的组合构成另外3种复杂情况。这7种情况是完备的，它们确实存在，有时不可避免。根据噪声系数测量的原理，推导了各种情况下的损耗修正公式，并详细分析了额外损耗对测量不确定度的影响。

Loss Correction Techniques for Noise Figure Measurement

In order to measure the true noise figure of DUT, corrections for extra losses should be made. Existing noise figure analyzer can only make corrections for losses before DUT, losses after DUT and their combination. But when a lossy component which is included in the calibration loop is not connected after the DUT in the measurement procedure, corrections are also needed. The combination of this new situation and the three existing cases forms three other complex situations. These seven situations are complete, they do exist and sometimes are unavoidable. According to the theory of noise figure measurement, derivation of loss correction formulae for all kinds of situation is presented and effects of extra losses on measurement uncertainties are studied in detail.