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Measurement Uncertainty Analysis – Power Reference Level Test
Measurement Introduction
Agilent E4416A/E4417A Service Guide B-3
where,
P
s
is the reflection coefficient of the source (i.e. the DUT) and P
d
is the reflection
coefficient of the 8478B detector.
Hence,
Consider the measurement setup that exists in Figure B-1
Figure B-1: Measurement Setup
P
o
is the total power output from the DUT. Of this power a proportion related to P
d
is
reflected back towards the source. The power subjected on the 432 would be:
But because a proportion of this total power related to Pd has been reflected Ps will
again cause a reflection giving:
So the total power incident or measured by the 432 Power meter is given by:
Note In all cases P
d
is extremely small therefore P
d
² terms tend to zero leaving.
P
meas
fV
comp
V
1
V
0
RCFM
s
,,,,,()=
DUT
432A
Power
Meter
8478B
POWER
REF
P
S
P
d
P
o
1P
d
2
–
P
o
1P
s
P
d
±()
2
P
o
1P
d
2
–
1P
s
P
d
±()
2
⁄