Agilent Technologies NFA Series, Performance Verification And Calibration Manual

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Chapter 2 55
Test Descriptions
Noise Figure Range and Accuracy
Noise Figure Range and Accuracy
Test Description
A precision step attenuator, calibrated at 50 MHz with an accuracy of 0.010dB, is
used as an external standard to measure the NFA’s Noise Figure Range and
Accuracy over a 22dB range. The results are then used to determine the Instrument
Uncertainty for the given ENR values over their respective measurement ranges.
A 50 MHz CW signal is passed through a precision step attenuator. The signal path
is referenced at 0dB attenuation. The attenuator is then stepped in 1dB steps from 1
to 11 taking the analyzers P
hot
measurement at each step. Only one step attenuator is
used in the measurement to reduce the overall measurement uncertainty of the
standard. It is therefore necessary to re-reference the measurement and repeat the
test covering the range from 12-22dB. All levels tested below 1dB are interpolated
from the measured points, as the minimum step attenuator setting is 1dB.
For test purposes the Noise Figure Range and Accuracy is only tested at the lower
frequency band with the most accurate specifications.
Test Specification
Related Adjustment
None
Table 2-10 N8973A, N8974A and N8975A specification
Noise Source ENR 4 - 7dB 12 - 17dB 20 - 22dB
Noise Figure Measurement Range 0 to 20dB 0 to 30dB 0 to 35dB
Instrument Uncertainty
±
0.05dB
±
0.05dB
±
0.10dB