Concepts and Features
R&S
®
ZNC
85
User Manual 1173.9557.02 ─ 13
Accuracy considerations
To ensure an accurate calibration, please observe the following items:
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Unused ports of the calibration unit must be terminated with a 50 Ω match.
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No adaptors must be inserted between the calibration unit and the test ports of the
analyzer.
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After connecting the unit to the USB port, allow for a sufficient warm-up time before
starting the calibration. Refer to the "Specifications" of the calibration unit for details.
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To ensure best accuracy the analyzer automatically reduces the source power to –
10 dBm. If the test setup contains a large attenuation, deactivate "Auto Power Reduc-
tion for Cal Unit" in the "Calibration" tab of the "System Config" dialog and ensure an
input power of –10 dBm at the ports of the calibration unit (please also refer to the
"Specifications" of the calibration unit).
Maximum RF input power
The maximum RF input power of the calibration unit is beyond the RF output power range
of the analyzer, so there is no risk of damage if the device is directly connected to the
test ports. If you use an external power amplifier, make sure that the maximum RF input
power of the calibration unit quoted in the data sheet is never exceeded.
The available calibration types depend on the number of ports. For a single calibrated
port, the reflection calibration types are available ("Refl Norm Open", "Refl Norm Short",
"Refl OSM").
For 2 ports, the analyzer provides the following additional calibration types:
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A single full 2-port (TOSM or UOSM) calibration.
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Two full one-port calibrations for the two calibrated ports.
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A one path two port calibration. The node port is the source port for the one path two
port calibration (fully calibrated port).
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A transmission normalization (bidirectional, forward or reverse). "Forward" transmis-
sion normalization means that the signal direction is from port 1 to port 2.
3.5.5.3
Characterization of Calibration Units
Each calibration unit is delivered with factory characterization data which ensure an
accurate calibration for all standard applications. For specific modifications of the test
setup, e.g. the connection of additional adapters to a calibration unit, a modified set of
characterization data (suitable for the cal unit with adapters) may be desirable. The R&S
ZNC provides a characterization wizard which you can use to generate your own char-
acterization data sets for (modified) R&S cal units. The characterization data can be
stored in the cal unit and used for automatic calibration whenever needed.
A cal unit characterization can be performed in a frequency sweep. The network analyzer
must be properly calibrated, with the reference plane at the input ports of the (modifed)
cal unit to be characterized.
Calibration
