R&S® ZVA-Z90E / -Z110E
Frequency Converters –
Basic Operation
Application Sheet
1ZKD-15, M. Jetter,
08/2009 ─ 02
Application Sheet
Test & Measurement
© 2009 Rohde & Schwarz GmbH & Co. KG
81671 Munich, Germany
Printed in Germany – Subject to change – Data without tolerance limits is not binding.
R&S® is a registered trademark of Rohde & Schwarz GmbH & Co. KG.
Trade names are trademarks of the owners.
The following abbreviations are used throughout this document: R&S® ZVA-ZxxxE is abbreviated as R&S ZVA-ZxxxE. The vector
network analyzer R&S® ZVA is abbreviated as R&S ZVA.
R&S® ZVA-Z90E / -Z110E
1 Basic Operation
This application sheet describes the use of an R&S ZVA vector analyzer and two
R&S ZVA-Z110E frequency converters for 2-port transmission measurements.
Measurements using other converter types are performed in an analogous way.
Basic Operation
Required Equipment
1.1 Required Equipment
Measurements with frequency converters can be carried out with the following equipment:
● Network analyzer (NWA) R&S ZVA with an upper frequency limit of 20 GHz or higher
(R&S ZVA 24, R&S ZVA40 ...).
The required firmware version depends on the frequency converter model:
- R&S ZVA-Z110E: at least version V2.61
- R&S ZVA-Z90E: at least version V2.70
● Two NWA ports per frequency converter port.
Alternatively: One NWA port per frequency converter plus a common external generator for the LO signals. The R&S SMF100A signal generator with suitable options
is recommended.
● N frequency converters for an N-port measurement
● Option R&S ZVA<n>-B16, "Direct Generator/Receiver Access" at each port
● Option R&S ZVA-K8, "Converter Control"
● Option R&S ZVA-B8 to establish the control connection between the NWA and the
frequency converters
● a suitable set of calibration standards
1.2 Measurement Principle
The frequency converters use frequency multipliers to transform the RF source signal
from one of the network analyzer ports into a high-frequency stimulus signal. A second
signal (Local Oscillator, LO) is used for down-conversion of the reference and measurement channels. The LO signal can be provided either by a second analyzer port or by an
external generator.
The measurement involves the following steps:
1. Selection of the converter and test setup, activation of the converter mode
2. Entry of power coefficients (when a converter is used for the first time or assigned to
a new analyzer port).
3. Connection of the frequency converters
4. Power and frequency settings
3Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
R&S® ZVA-Z90E / -Z110E
5. Power calibration using an appropriate external waveguide power meter
6. Calibration using a suitable waveguide calibration kit
7. Connection of the DUT and measurement
Basic Operation
Activating the Frequency Converter Mode
1.3 Activating the Frequency Converter Mode
To activate the converter mode for a setup without external generator,
1. Click "System > System Config ..." and open the "Frequency Converter" tab of the
"System Configuration" dialog.
2.
Select correct "Type": R&S ZVA-Z90E or R&S ZVA-Z110E.
3. If you use your frequency converter for the first time, click "Coefficients" to enter the
power coefficients; see chapter 1.4, "Entering Power Coefficients", on page 5.
4. Click "Apply" to activate the frequency converter mode and "Close".
Analyzer settings with active frequency converter
In frequency converter mode, the frequency and level settings of the network analyzer
are automatically set to be compatible with the selected frequency converters. "Low
Phase Noise" is enabled, Automatic Level Control (ALC) is disabled. The frequency and
levels of all ports are displayed in the "Port Configuration" dialog ("Channel > Mode >
Port Config …").
4Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
R&S® ZVA-Z90E / -Z110E
Basic Operation
Entering Power Coefficients
Fig. 1-1: Frequency Converter dialog (example: R&S ZVA-Z110E)
1.4 Entering Power Coefficients
For accurate control of the converter output power, the R&S ZVA analyzer must know
the (non-linear) current-power characteristic of the converters. The characteristic is sufficiently described by a third-order polynomial. A label with the four polynomial coefficients
c0, c1, c2, and c3 is affixed to each converter.
The power coefficients must be adjusted whenever a new converter is connected to an
analyzer port. To enter the coefficients, proceed as follows:
1. Activate the frequency converter mode following the first steps in chapter 1.3, "Acti-
vating the Frequency Converter Mode", on page 4.
2. In the "Frequency Converter" dialog, press "Coefficients".
3. In the "Power Coefficients" dialog opened, clear "Use default coefficients" and enter
your coefficients into the appropriate table row.
The numbers of the table rows denote the analyzer port for the converter.
4. Repeat the last step for all frequency converters in the test setup.
5Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
R&S® ZVA-Z90E / -Z110E
Fig. 1-2: Entry of power coefficients for analyzer port 1
Basic Operation
Connecting the Frequency Converters
1.5 Connecting the Frequency Converters
Each frequency converter must be connected to the analyzer, the power supply and the
DUT.
● Control connection: Connect the 3-pin control connector at the rear panel of the converter to the output connector of option R&S ZVA-B8 (EXT ATT CTRL) at the top right
of the R&S ZVA front panel using the control cable supplied with the converter.
● Analyzer ports: Connect each of the two frequency converters as shown in the "Frequency Converter" tab of the "System Configuration" dialog using the cables for the
REF OUT and MEAS OUT signals supplied with the converters and two additional,
high-quality coaxial cables.
● Power supply: Connect the external DC power supply provided with the converter to
the "9 V / 0.5 A" DC input.
● DUT (usually connected after calibration): Screw on the waveguide flange.
Refer to the quick start guide of your converter for details.
1.6 Power and Frequency Settings
While the frequency converter mode is active, the "Channel > Stimulus" settings of the
network analyzer control the frequency and power range of the converters. In addition
the "Channel > Mode > Port Configuration" dialog shows an additional row for each converter. The "Frequency" and "Power" settings in the "Source" section of the dialog serve
different purposes:
● The output power for each converter can be selected in the "Power" column. A source
power calibration of the converter port ensures that the analyzer will generate the
selected source power; see chapter 1.7, "Calibration", on page 7.
6Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
R&S® ZVA-Z90E / -Z110E
● The source frequency at the converter ports is essentially determined by the port
frequency of the analyzer. The converter frequency settings in the "Port Configuration" dialog define the frequency axes for the source power calibrations, however,
they do not actually affect the converter output frequencies. For best accuracy,
ensure that the correct converter frequencies are set, especially if the test setup contains additional frequency-converting components.
Example:
In the example below, the frequency at the NWA "Port 1" has been increased by a 50
MHz offset. The converter source frequency six times the NWA source frequency, therefore a 300 MHz offset has been entered for "Converter Port 1". This ensures a correct
frequency axis during the power calibration.
Basic Operation
Calibration
Fig. 1-3: Converter frequency and power settings (example: R&S ZVA-Z110E)
1.7 Calibration
A source power calibration for a frequency converter requires an appropriate external
power meter, to be connected to the converter's waveguide flange. Waveguide power
meters are configured in the ordinary way using the "System Configuration > External
Power Meters" tab.
To perform the source power calibration, proceed as follows:
1. Connect the waveguide power meter and open the "Channel > Calibration > Start
Power Cal > Source Power Cal" dialog.
2. Select your converter and source port from the "Source" pull-down list (e.g. "Conv
1" for a frequency converter connected to NWA port 1).
3. Click "Modify Settings" and ensure that both "Flatness Cal" and "Reference Receiver
Cal" are checked.
4. If your test setup causes strong nonlinear effects, you can choose a "Convergence
Factor" different from one.
7Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
R&S® ZVA-Z90E / -Z110E
5. Start the calibration sweep.
To ensure an accurate source power calibration and quick convergence, use the correct
power coefficients; see chapter 1.7, "Calibration", on page 7.
A receiver power calibration of the b-waves (without external power meter, using the
“Receiver Power Calibration” dialog) is possible after completed source power calibration.
After the power calibration procedure a system error correction is recommended. Due to
the physical properties of the mm-waves and the waveguides, measurements with frequency converters require a special calibration kit for system error correction. Rohde &
Schwarz offers kits for this purpose, e.g. the calibration kits R&S ZV-WR10 and R&S ZVWR12. The standards in the calibration kit allow all one-port and two-port calibration types
supported by the network analyzer except TNA. Refer to the documentation of the calibration kit or the help system of your network analyzer for details.
Basic Operation
Measurement
1.8 Measurement
After power calibration and system error correction, the mm-wave measurement can be
performed like any other network analyzer measurement. The analyzer may perform a
frequency or power sweep. The "Port Configuration" settings (together with the "Stimulus" settings), determine the sweep range of the converted signals (for a frequency
sweep, the input and output frequencies at the DUT ports). All measured quantities (Sparameters, wave quantities, ratios etc.) and other trace settings are available.
The following example shows the transmission and reflection coefficients of a bandpass
filter in the frequency range between 75 GHz and 110 GHz, which is covered by the
frequency converter R&S ZVA-Z110E.
8Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
R&S® ZVA-Z90E / -Z110E
Basic Operation
Additional Information
Fig. 1-4: Transmission and reflection of a bandpass filter measured with an R&S ZVA-Z110E
For best measurement accuracy, observe the following rules:
● Enter the correct power coefficients of all frequency converters; see chapter 1.4,
"Entering Power Coefficients", on page 5.
● Perform a source power calibration; see chapter 1.7, "Calibration", on page 7. Using
converter output powers outside the calibrated range generally impairs the measurement accuracy. The effect is enhanced if the power coefficients are not correct.
● Perform a system error correction for the power-calibrated test setup using an appropriate test setup.
1.9 Additional Information
For a comprehensive description of the frequency converter mode including remote control refer to the R&S ZVA/ZVT online help system or to the printable operating manual,
which is available for download at http://www.rohde-schwarz.com/product/zva.
For an description of the R&S ZVA-Z110E connectors and safety instructions refer to the
R&S ZVA-Z110E Quick Start Guide.
Application notes related to the frequency converter are also available for download, see
http://www.rohde-schwarz.com/product/zva-z.
9Application Sheet 1ZKD-15, M. Jetter, 08/2009 ─ 02
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