General Operating Information 2
Keysight U2020 X-Series User’s Guide 67
S-Parameter correction
Figure 2-29 Non-ideal 2-port device
A DUT that has n number of ports has n
2
S-Parameters. These S-Parameters
represent reflected energy which interferes with the power measurements. These
errors are usually caused by additional components such as attenuators,
adapters, or matching pads, which are inserted between the DUT and the U2020
X-Series. Typically, DUTs are non-ideal, as illustrated in Figure 2-29. When power
is transmitted from the DUT, the U2020 X-Series will reflect a part of its incident
wave back to the 2-port device. The 2-port device will reflect this wave back to
the U2020 X-Series. The power from the DUT may therefore be calculated as
follows:
This feature enables you to correct for the effect of 2-port devices in your test
setup. You may load the values in table form directly into the U2020 X-Series via
SCPI commands as an S-Parameter table to be used for calculation.
The S-Parameter correction function is only available in U2020 X-Series power
sensors with firmware version A.04.04 and above.
b
1
a
2
S
12
S
21
S
11
S
22
a
1
b
2
b
DUT
DUT
Γ
DUT
≠ 0
Port 1 Port 2
b
DUT
b
2
1S
11
Γ
DUT
–()1S
22
Γ
L
–()
S
21
--------------------------------------------------S
12
Γ
DUT
Γ
L
–=
– The U2020 X-Series supports up to 10 S-Parameter tables that are retained
across reset and power cycles.
– For more details on SCPI commands, refer to the U2020 X-Series
Programming Guide.
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