11 | Keysight N1911A/N1912A P-Series Power Meters and N1921A/N1922A Wideband Power Sensors - Data Sheet
Graphical Example
A. System contribution to measurement uncertainty versus power level (equates to step 6 result/2)
System uncertainty contribution - 1 sigma (%)
100.0%
N1921A: 500 MHz to 10 GH
N1922A:18 to 40 GHz
Other bands
10.0%
1.0%
Note: This graph is valid for condi-
tions of free-run operation, with a
signal within the video bandwidth
setting on the system.
-35 -30 -25 -20 -15 -10 -5
0
5
10 15 20
Power (dBm)
Humidity < 70%.
B. Standard uncertainty of mismatch.
Standard uncertainty of mismatch - 1 sigma (%)
SWR
1.0
ρ
SWR
1.8
ρ
0.5
0.45
0.4
0.00
0.02
0.05
0.07
0.09
0.11
0.13
0.15
0.17
0.18
0.20
0.23
0.26
0.29
0.31
0.33
0.35
0.38
0.39
0.41
0.43
0.44
0.46
0.47
0.49
0.50
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
1.45
1.5
1.90
2.00
2.10
2.20
2.30
2.40
2.50
2.60
2.70
2.80
2.90
3.00
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
1.6
1.7
0
0.1
0.2
0.3
0.4
0.5
r
DUT
Note: The above graph shows the standard uncertainty of mismatch = ρDUT. ρSensor / ←2, rather than the mismatch uncertainty
limits. This term assumes that both the source and load have uniform magnitude and uniform phase probability distributions.
C. Combine A & B
(Value from Graph A)2+ (Value from Graph B)2
UC
=
Expanded Uncertainty, k = 2, = 2. UC = . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
%
KEYSIGHT [ Keysight Technologies ]
