Atec Agilent-8757D - Manual (Page 6)

6
Transmission measurement accuracy
Transmission loss or gain measurements are made
relative to a 0 dB reference point established at
calibration.
Transmission measurement uncertainty =
dynamic power accuracy + mismatch uncertainty
Dynamic power accuracy is the measurement
uncertainty due to the change in power level
between calibration and the measurement.
Mismatch uncertainty is the uncertainty due to
reflections in the measurement setup. The frequency
response errors of the source, detectors, bridge,
and power splitter are removed via calibration.
Transmission measurement uncertainty examples
Assumptions:
• Measurement frequency = 10 GHz
• DUT input/output SWR = 1.5
• Ratio measurement
Change in power after calibration
<30 dB (+0 to –30 dBm range)
85037B 85025E
Uncertainty component precision detector detector
Dynamic accuracy (±dB) 0.11 0.40
Mismatch (±dB) 0.45 0.33
Total (±dB) 0.56 0.73
Change in power after calibration
60 dB (+6 to –55 dBm range)
85037B 85025E
Uncertainty component precision detector detector
Dynamic accuracy (±dB) 0.96 2.00
Mismatch (±dB) 0.45 0.33
Total (±dB) 1.41 2.33
Absolute power measurement accuracy
This specification is useful for determining the
accuracy of power measurements in dBm when
using the Agilent 85037 series precision detectors
or the 85025 series detectors in DC mode.
Absolute power uncertainty =
absolute power accuracy at 50 MHz + frequency
response + mismatch uncertainty
Absolute power measurement uncertainty examples
Assumptions:
• Measurement frequency = 10 GHz
• DUT input/output SWR = 1.5
Power = +10 dBm
85037B 85025E
Uncertainty component precision detector detector
Absolute power accuracy
at 50 MHz (±dB)
0.11 0.50
Frequency response (±dB) 0.18 0.50
Mismatch (±dB) 0.18 0.10
Total (±dB) 0.47 1.10
Power = 0 dBm
85037B 85025E
Uncertainty component precision detector detector
Absolute power accuracy
at 50 MHz (±dB)
0.11 0.40
Frequency response (±dB) 0.18 0.50
Mismatch (±dB) 0.18 0.10
Total (±dB) 0.47 1.00
Power = 50 dBm
85037B 85025E
Uncertainty component precision detector detector
Absolute power accuracy
at 50 MHz (±dB)
0.85 1.30
Frequency response (±dB) 0.18 0.50
Mismatch (±dB) 0.18 0.10
Total (±dB) 1.21 1.90
System accuracy