Agilent Technologies E4416A Service Manual page 159

C Measurement Uncertainty Analysis - Power Reference Level Test
So the total power incident or measured by the Agilent 432 Power meter is
given by:
( (
P 1 P
o
In all cases P
N O TE
M Uncertainty
s
The equation above includes the worst- case mismatch magnitude 2P
in the form where various powers can be multiplied by the equation to find
worst- case power levels with respect to mismatch.
From the above mismatch uncertainty equation if Pd is zero, for example, the 8478B
N O TE
sensor is exactly 50 ohms then there is NO mismatch uncertainty. This has not yet been
achieved but efforts will be made in the future to try to achieve as near as possible to a
'zero' level of mismatch uncertainty and hence have negligible mismatch when
calibrating products.
C-138
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2 2
) ) ⁄ ( ± )
– 1 P P
d s d
is extremely small therefore P
d
⁄ ( ±
= 1 1 2P
s
²
terms tend to zero leaving.
d
)
P
d
E4416A/E4417A Power Meters Service Guide
P and is
s d