A Calibration Unit is an integrated solution for automatic system error calibration of vector network analyzers of the R&S ZVAB family. Rohde & Schwarz provides different types of calibration units:
The 4-port calibration units R&S ZV-Z51 (order numbers 1164.0515.30 or 1164.0515.70 for models equipped with 3.5 mm or type N sockets, respectively) are especially suited for R&S ZVB and R&S ZVA vector network analyzers in the frequency range up to 8 GHz.
The calibration units R&S ZV-Z52 (order numbers 1164.0521.30 and 1164.0521.72 for models equipped with 3.5 mm or type N sockets) are especially suited for R&S ZVB and R&S ZVA vector network analyzers in the frequency range up to 18 GHz (model 72, 2 ports) or up to 24 GHz (model 30, 4 ports).
The 8-port calibration unit (accessory R&S ZV-Z58, order number 1164.0638.78) are especially suited for R&S ZVT vector network analyzers.
The units contain calibration standards that are electronically switched when a calibration is performed. The calibration kit data for the internal standards are also stored in the calibration unit, so that the analyzer can calculate the error terms and apply the calibration without any further input.
Advantages of automatic calibration
Automatic calibration is generally faster and more secure than manual calibration, because:
There is no need to connect several standards manually. The number of connections to be performed quickly increases with the number of ports; see TOSM Calibration.
Invalid calibrations due to operator errors (e.g. wrong standards or improper connections) are almost excluded.
No need to handle calibration kit data.
The internal standards don't wear out because they are switched electronically.
Limitations
Automatic calibration is less flexible than manual calibration:
Only full one port or TOSM calibrations can be performed automatically, see overview table.
Only fixed groups of ports can be calibrated, e.g. port 1 and 2, port 1, 2, and 3. This restriction does not hold in remote control; see [SENSe<Ch>:]CORRection:COLLect:AUTO.
Attention!
Please observe the safety instructions on the technical information provided with the calibration unit to avoid any damage to the unit and the network analyzer. Safety-related aspects of ZV-Z51/-Z52/-Z58 connection and operation are also reported in the sections below.
Connecting the calibration unit
Performing an automatic calibration
The calibration units provide the following connectors:
Calibration units R&S ZV-Z51/-K52
A USB type B connector at the rear is used to power-supply and control the unit. A USB cable for connection to the network analyzer is provided with the calibration unit.
Two or four RF connectors numbered 1 to 4 are to be connected to the test ports 1 to 4 of the analyzer. The connector type is either type N (f) or 3.5 mm (f) for all four connectors.
Calibration units R&S ZV-Z58
A USB type B connector at the front is used to control the unit. A USB cable for connection to the network analyzer is provided with the calibration unit.
The RF connectors numbered 1 to 8 are to be connected to the corresponding test ports of the analyzer. The connector type is type N (f) for all connectors.
To connect the unit...
Switch on and start-up your network analyzer.
To protect your equipment against ESD damage use the wrist strap and grounding cord supplied with the instrument and connect yourself to the GND connector at the front panel.
Connect the USB type A connector of the USB cable to any of the USB type A connectors on the front or rear panel of the analyzer. Connect the USB type B connector of the USB cable to the USB type B connector of the calibration unit. You can also connect the unit before switching on the analyzer.
Wait until the operating system has recognized and initialized the new hardware. When the unit is connected for the first time, this may take longer than in normal use.
The unit is ready to be used, see Performing an automatic calibration.
Note:
The calibration unit is intended for direct connection to ZVA network analyzers following the procedure described above. You can also connect the unit before switching on the analyzer. Do not connect the unit to other USB hosts, e.g. a PC, or insert any USB hubs between the analyzer and the unit, as this may cause damage to the unit or the host.
You can connect several calibration units to the different USB ports of the analyzer. You can also connect cal units and other devices (mouse, USB memory stick etc.) simultaneously.
An unused calibration unit may remain connected to the USB port while the network analyzer is performing measurements. It must be disconnected during a firmware update.
It is safe to connect or disconnect the calibration unit while the network analyzer is operating. Never connect or disconnect the unit while data is being transferred between the analyzer and the unit. Never connect the unit during a firmware update.
After connection and initialization, you can use the calibration unit as follows:
Connect ports 1 through n (n = 1 to 8, depending on your analyzer and calibration unit model and the number of ports to be calibrated) of the analyzer to n arbitrary ports of the calibration unit. Terminate all unused ports (no. n + 1 to 2, 4, or 8) with a 50 W match.
Perform the automatic calibration for the selected number of ports using the Measurement Wizard or the Start Calibration menu.
Remove the test cables from the unit, connect your DUT instead and perform calibrated measurements.
The assignment between the analyzer ports and the cal unit ports is detected automatically. If auto-detection fails (e.g. because of a high attenuation in the signal path), connect matching port numbers and click Default Port Assignment at the beginning of the calibration process.
Accuracy considerations
To ensure an accurate calibration, please observe the following items:
Unused ports of the calibration unit must be terminated with a 50 W match.
No adaptors must be inserted between the calibration unit and the test ports.
After connecting the unit to the USB port, allow for a sufficient warm-up time (see "Specifications") before starting the calibration.
To ensure best accuracy the analyzer automatically reduces the source power to –10 dBm. If the test setup contains a large attenuation, deactivate Automatic Power Reduction for Calibration Unit in the initial 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 separate "Specifications" document).
In manual control, a 1-port calibration can be performed at port 1 or port 2, a 2-port calibration at ports 1 and 2 etc; see tables below. To perform any calibrated measurement using port 3 or 4, a 3- or 4-port calibration is required.
In remote control mode, an arbitrary assignment between the analyzer and the calibration unit ports is possible. This is important for the calibration of ports 3 and 4 with a 2-port unit R&S ZV-Z52, var. 72.
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 calibration type depends on the number of ports:
ZV-Z51/-Z52: Number of ports calibrated
Calibration type
1 (port 1 or port 2)
Full one port
2 (ports 1 and 2)
TOSM
3 (ports 1, 2, and 3 or ports 1, 2, and 4)
4 (ports 1, 2, 3, and 4)
ZV-Z58: Number of ports calibrated
4 (ports 1 to 4)
5 (ports 1 to 5)
6 (ports 1 to 6)
7 (ports 1 to 7 or ports 1 to 6 and port 8)
8 (ports 1 to 8)
Messages during the calibration process
The automatic calibration is started on clicking Calibration Unit in the Start Calibrationmenu. When the test port connectors in the Port Configuration dialog do not fit to the connectors of the calibration unit, a warning appears:
OK changes the connector type assignment of the test ports and starts the calibration. The Calibration Unit dialog shows the parameters of the cal unit, port assignment, and the progress of the calibration procedure.
In the dialog, you can:
Select Other Cal Unit in case that several cal units are connected to the analyzer.
Detect the current port assignment between the analyzer and the connected calibration unit
Restore the Default Port Assignment (connect port no. n of the analyzer to port no. n of the cal unit). This is important if the automatic detection of the port assignment fails.
Start the necessary calibration sweeps. The calibration is started automatically if automatic port detection is successful and the cal unit temperature is within the validity range.
Abort an ongoing calibration process.
The Calibration Unit dialog is closed automatically when all standards have been measured, the system error correction data have been calculated, and the result is applied to the active channel. The network analyzer is ready to perform calibrated measurements.
Remote control:
[SENSe<Ch>:]CORRection:COLLect:AUTO [SENSe<Ch>:]CORRection:COLLect:AUTO:PORTs [SENSe<Ch>:]CORRection:COLLect:AUTO:PORTs:CONNection?