The Mode menu defines the properties of the physical and logical (balanced) test ports, configures the source signals and the receiver, and provides special measurement modes. Many of the measurement modes require option R&S ZVA-K4, Arbitrary Generator and Receiver Frequencies.
The items in the submenu depend on the analyzer type and on the installed options.
Port Config... opens a dialog to define the properties of the test ports, the source and the receiver.
ZVAX Path Config configures the RF signal paths in the Extension Unit R&S ZVAXxx and the installed hardware modules. The command is unavailable if no RZS ZVAXxx unit is connected.
Harmonics provides arbitrary harmonic distortion measurements including power calibration.
Scalar Mixer Meas measures the mixing products generated by an external mixer that is supplied with two independent RF signals.
Mixer Delay Meas gives access to the measurement of the absolute or relative group delay of a mixer.
Intermod Distortion Meas opens a submenu to control intermodulation distortion measurements including power calibration.
Noise Figure Meas configures and activates the measurement of the noise figure of a DUT.
Virtual Transform defines the parameters of a virtual matching network to be used for embedding/deembedding a DUT with single ended or balanced ports.
Defined Coherence Mode... activates the operating mode where the analyzer generates several continuous signals with specific relative amplitude and phase (with option R&S ZVA-K6, True Differential Mode)
Alternating Sweeps activates or deactivates the operating mode where the analyzer performs only one partial measurement per sweep.
Pulse Generator turns the pulse generator on or off.
Def Pulse Generator defines the properties of the pulse generator signals.
Spurious Avoidance defines the relative position of the local oscillator (LO) relative to the RF input signal.
ALC (All Chans) enables or disables the Automatic Level Control for all channels.
Low Phase Noise reduces the phase noise of the source signals.
The Port Configuration dialog defines the properties of the test ports and configures the source signals and the receiver.
The table in the Port Configuration dialog contains the individual test port properties. Each table row corresponds to one logical or physical port; the number of rows is equal to the number of test ports of the analyzer.
Many measurement tasks can be performed with default port settings. Consequently the Port Configuration dialog does not show all columns in its default configuration. Use the Displayed Columns button to customize the table and display or hide columns.
Measured Ports (Meas/Group)
The ports that can be used for the measurement (as selected in the Balanced Ports and Port Groupsdialog) are indicated in the first column of the Port Configuration table (Meas). The selected ports are used for the calculation of derived (mixed mode, Z, Y) parameters; they can be source ports and/or receive ports.
After an n-port (automatic or manual) system error correction, only the calibrated ports are enabled. It is possible though to re-enable uncalibrated ports manually in order to obtain additional (uncalibrated) measurement results. Loading a set of calibration data does not affect the selection of measured ports.
A measured port can be configured as a pure receive port by selecting RF Off in the Source section.
If one or more port groups to be measured are defined in the Define Measured Portstab of the Balanced Ports and Port Groups dialog, then the column header changes from Meas. to Group and the column shows the group names (capital letters).
The settings are grouped together in four sections:
Logical Port shows the properties of the balanced ports after they have been defined in the Balanced Port and Port Groups dialog. This section is hidden if no balanced ports are defined.
Physical Port shows and/or defines the properties of the physical (unbalanced) ports of the analyzer.
Source shows and/or defines the generator settings at each physical port of the analyzer.
Receiver shows and/or defines the receiver settings at each physical port of the analyzer.
Below the table, three buttons open additional dialogs:
Displayed Columns... customizes the port configuration table by displaying or hiding columns.
Balanced Ports and Port Groups... selects a balanced port configuration and defines the reference impedances at the ports.
Stimulus modifies all sweep frequencies and powers in the active channel, based on an arbitrary frequency and power reference.
The dialog contains the following additional controls:
If Same Connector Type at All Ports is active, the connector types at all ports (but not necessarily their gender) are always adjusted to the current selection in the Connector column.
If Same Gender at All Ports is active, the connector genders at all ports (but not necessarily their types) are always adjusted to the current selection in the Connector column.
Measure Source Port Waves at qualifies whether the waves at each source port are measured at the selected receiver or source frequency. The setting affects both the reference receiver (waves an) and the measurement receiver (waves bn) while port n is used as a source port. Adjust the setting to the test setup and the measured quantity.
Freq Conv Off disables all power and frequency-converting modes, i.e. it resets all port frequencies to the basic channel frequency, sets the power to the base power of the channel, and disables frequency-converting measurements such as the Harmonics and the Mixer measurements (with option R&S ZVA-K4).
S-parameter measurements for port configurations with different frequencies are not fully supported; see S-Parameters in Frequency-Converting Modes.
Remote control:
[SENSe<Ch>:]CORRection:COLLect:CONNection:PORTs ALL | SINGle [SENSe<Ch>:]CORRection:COLLect:CONNection:GENDers ALL | SINGle [SENSe<Ch>:]FREQuency:CONVersion:AWReceiver[:STATe]
Defines the properties of the logical (balanced) ports defined in the Balanced Port and Port Groups dialog. To display this section, at least one balanced port configuration must be defined and Logical Ports – Ref Impedance must be selected in the Displayed Columns dialog.
# is the port number of the logical port. This number is independent of the physical port numbers and of the ports that are combined to form a balanced port.
Ref Impedance shows the complex reference impedances of the ports.
Reference impedance settings
The default reference impedance for a physical port is equal to the reference impedance of the connector type assigned to the port but can be defined as an arbitrary complex value (renormalization of port impedances). By changing the reference impedance, it is possible to convert the measured values at 50 Ω (75 Ω) into values at arbitrary port impedances. For details refer to Virtual Transform –Reference Impedances.
For balanced ports it is possible to define separate complex reference impedances for differential and for common mode.
The default values for the balanced port reference impedances are derived from the default reference impedance of the physical analyzer ports (Z0 = 50 >Ω):
The default value for the differential mode is Z0d = 100 Ω = 2*Z0.
The default value for the common mode is Z0c = 25 Ω = Z0/2.
SENSe:PORT<phys_port>:ZREFerence <real> [,<imaginary] SENSe:LPORT<log_port>:ZCOMmon <real> [,<imaginary] SENSe:LPORT<log_port>:ZDIFferent <real> [,<imaginary] CALCulate<Chn>:TRANsform:IMPedance:RNORmal TWAVes | PWAVes
Shows and/or defines the properties of the physical (unbalanced) ports of the analyzer.
# is the test port number of the analyzer as shown on the front panel. External generators and power meters configured in the System Configuration dialog are also shown in the list of physical ports.
Instrum. shows the network analyzer type (e.g. ZVA8, ZVA24). The types of external generators and power meters are also displayed in this column.
Connector opens a drop-down list to select the connector type An (f) behind the connector type denotes female connectors, an (m) denotes male connectors. Symmetric (sexless) connectors (e.g. PC7) are not labeled. User-defined connectors can be added or removed in the Available Connector Types dialog, which is opened from the Channel –Calibration –Calibration Kits dialog. at the port and its gender. If Same Connector at All Ports is active, the connector types at all ports (but not their gender) are always adjusted to the current selection.
Ref. Impedance shows the adjustable complex reference impedances of the physical port. For background information refer to Reference Impedances. If a balanced port configuration is active the reference impedance settings for all ports are displayed in the Logical Port section. For external generators and frequency converters, no reference impedance settings are available. The reference impedance for external power meters must be real; no wave theory selection is required. If a value Re(Z0) other than 50 Ω is entered, the power result from the power meter is multiplied by the factor 50 Ω / Re(Z0) (conversion of the reported power to a voltage at 50 Ω, then re-conversion to a power using Re(Z0)).
To perform a system error correction, the physical port must be available as a source and receive port. This condition is met if it is selected as a measured port in the Balanced Ports and Port Groups dialog (Meas is on).
To perform a system error correction, it is necessary that:
the physical port is available as a source port
both the measurement and the reference channel at the port can be measured
These conditions are met with the Port Configuration settings listed below.
Section
Parameter
Value
Meas
On
on
Source
Perm
off
Receiver
LO a
LO b
[SENSe<Ch>:]CORRection:COLLect:CONNection<port_no> [SENSe<Ch>:]CORRection:COLLect:SCONnection<port_no> [SENSe<Ch>:]CORRection:COLLect:CONNection:PORTs ALL | SINGle SENSe:PORT<phys_port>:ZREFerence <real> [,<imaginary]
Shows and/or defines the RF generator settings for each physical port of the analyzer and for each external generator. No source settings are provided for external power meters.
Most of the settings in this section require option ZVA-K4, Arbitrary Generator and Receiver Frequencies.
RF Off switches the RF signal source at the port off (box checked) or on. Dependencies: The column is disabled (grayed) while the RF power is switched off globally for the active channel. The settings are restored as soon as the RF power is switched on again. RF Off and Meas are independent from each other: While the RF power is switched off, the port is not necessarily excluded from the measurement, it can still be used as a receive port. On the other hand, an excluded port (Meas = Off) can still be used as an RF signal source. The exact behavior of RF Off is part of the system configuration; refer to the description of the Power tab.
The source must be switched on to perform a system error correction or a source power calibration for the source port.
Gen qualifies whether the RF signal source at the port is switched on for all partial measurements (box checked, permanent signal source) or only for the partial measurements that require the port as a drive port. Dependencies: Gen has no effect unless the RF source at the port is switched on (RF Off is not checked). A port which is excluded from the measurement (Meas = Off) can still be used as a permanent RF signal source. If Gen is on, then the source frequencies at port 1 and 2 and at port 3 and 4 are coupled; see note on coupled test ports below. Gen is unavailable in true differential mode.
External generators
An external generator always represents a permanent signal source that is switched on for all partial measurements. Gen qualifies whether or not the generator is actually available as a signal source in the test setup.
The analyzer provides two alternative ways of selecting a generator as a signal source:
Gen: On in the Port Configuration dialog, especially if the generator is not assigned to a particular measured quantity or drive port.
Selection as a source for a particular measured quantity or for a power calibration, see e.g. More Wave Quantities.
The two selection mechanisms are independent from each other.
Permanent vs. intermittent RF signal source
Switching on the signal source permanently eliminates the power settling times of the DUT but may introduce measurement inaccuracies, e.g. due to crosstalk between two ports. Therefore, the parameter must be switched off to perform a system error correction.
Frequency opens an input box to define a port-specific stimulus frequency range (for frequency sweeps) or CW frequency (for power, time and CW Mode sweeps). In the default configuration the stimulus parameters (sweep range, CW Frequency) are used. The result is displayed in the Frequency Result column. A red Frequency field indicates that the hardware limits are exceeded, e.g. if the default sweep range of the analyzer is beyond the frequency range of the external generator. The port-specific frequency for frequency converter ports can be defined in a separate dialog; see Converter Port <n> Frequency.
Coupled test ports
Test ports 1 and 2 and test ports 3 and 4 are supplied by a common generator as shown below. For R&S ZVT analyzers, ports 5 and 6 and ports 7 and 8 (if available) are coupled in an analogous way.
If the RF signal is simultaneously fed to two coupled ports (i.e. if Gen is switched on so that at least one signal source is permanent), the port frequencies must be the same. For normal measurements (Gen switched off), this restriction does not apply because there is only one source port per partial measurement.
The frequency formula for a permanent signal source is also used for the second (coupled) test port.
On R&S ZVA-Z67 network analyzers, all ports have independent internal sources. You can configure and combine the ports without restrictions.
Frequency Result displays the current frequency range (for frequency sweeps) or CW frequency (for power, time and CW Mode sweeps); see stimulus parameters.
Power opens an input box to define a port-specific source power range (for power sweeps) or fixed power (for frequency and CW sweeps). The result (not taking into account a possible Slope) is indicated in the Power Result column. In the default configuration the stimulus parameters (sweep range, internal source Power) are used. The port-specific power for frequency converter ports can be defined in a separate dialog; see Converter Port <n> Power.
Power Result displays the current power range (for power sweeps) or fixed internal source power (for frequency, time and CW Mode sweeps); see stimulus parameters.
PCor Off enables or disables a source power calibration for an individual port. This function is available only for ports where a source power calibration is available. It is identical with Source Power Correction Off in the Source Power Cal menu.
Slope defines a linear factor to modify the port-specific source power as a function of the stimulus frequency. The Slope factor increases the power at each sweep point by the following amount: Power --> Power + <Slope>*<Stimulus Frequency>. Slope is valid for all sweep types.
ALC defines port-specific Automatic Level Control (ALC) settings (entries a1, a2 ...) or general ALC settings (entries Off).
Impact of the Slope
The channel base power pb is defined by the following sweep settings:
For a power sweep, the channel base power is equal to the stimulus range.
For a frequency or CW sweep, the channel base power is a fixed Powervalue.
The slope modifies the channel power pb so that the following source power ps is obtained at the ports:
ps = pb + <Slope> * f
In the formula above, f denotes the (current) source port frequency.
Examples:
1. Select a frequency sweep with a sweep range between 1 GHz and 4 GHz and set <Power> = 0 dBm, <Slope> = 2 dB/GHz. Across the sweep range, the stimulus power increases linearly between 2 dBm and 8 dBm.
2. Maintain the <Slope> setting and select a power sweep with a CW frequency of 1 GHz and a power sweep range between –25 dBm and 0 dBm. Due to the slope factor, the actual stimulus power varies between –23 dBm and +2 dBm.
With option R&S ZVA-K4, the source power can be modified; see Port-Specific Power.
SOURce<Ch>:POWer<Pt>:STATe ON | OFF SOURce<Ch>:POWer<Pt>:GENerator:STATe ON | OFF SOURce<Ch>:POWer<Pt>:PERManent[:STATe] ON | OFF [SENSe<Ch>:]FREQuency:STARt? [SENSe<Ch>:]FREQuency:STOP? [SENSe<Ch>:]SWEep:CW|FIXed? SOURce<Ch>:POWer<Pt>[:LEVel][:IMMediate]:OFFSet SOURce<Ch>:POWer[:LEVel][:IMMediate][:AMPlitude]? SOURce<Ch>:POWer<Pt>:CORRection[:STATe] SOURce<Ch>:POWer<Pt>[:LEVel][:IMMediate]:SLOPe SOURce<Ch>:POWer<Pt>:GENerator<Gen>:OFFSet SOURce<Ch>:POWer<Pt>:GENerator<Gen>:PERManent[:STATe]
Shows and/or defines the receiver settings for each physical port of the analyzer and each external power meter. No receiver settings are provided for external generators.
Some receiver settings can be defined independently for the reference channel a (the wave generated by the internal source and measured at the port) and the measurement channel b (the wave from the DUT) at each port.
LO a/b switch the two Local Oscillator amplifiers at the port on (box checked) or off.
Both LOs must be switched on to perform a system error correction.
Frequency opens an input box to define a converted receiver frequency range (for frequency sweeps) or CW frequency (for power, time and CW Mode sweeps). The converted receiver frequencies are valid for all ports. In the default configuration the stimulus parameters (sweep range, CW Frequency) are used. The result is indicated in the Frequency Result column.
PCor Off enables or disables a receiver power calibration for an individual port. This function is available only for ports where a receiver power calibration is available. It is identical with Receiver Power Correction Off in the Receiver Power Cal menu.
Δ Frequency a', b' defines the port-specific frequency offset of the primed wave quantities relative to the unprimed quantities; see Measurements at Different Frequencies. The port-specific offset is added to the common frequency offset (Frequency...). The result is indicated in the Frequency a', b' Result column.
Atten defines port-specific attenuation factors for the received wave. The settings are analogous to the global Step Attenuator settings and replace them.
IF Gain a and IF Gain b select the IF gain in the reference receiver and measurement receiver path, respectively. IF Gain a is not available on R&S ZVT20 analyzers.
Receiver path settings and AGC
The IF Gain settings are valid for all ports:
Auto means that the analyzer adapts the IF gain to the RF input level (Automatic or Adaptive Gain Control, AGC). The A/D converter is always operated at optimum input level.
The following settings accelerate the measurement:
Low Dist(ortion) corresponds to a small IF gain(i.e. a lower internal A/D converter input level). This setting allows for a high RF overdrive reserve and is appropriate for high RF input levels.
Low Noise corresponds to a large IF gain(i.e. a higher internal A/D converter input level). This setting increases the dynamic range and is appropriate for low RF input levels.
The Low Dist or Low Noise settings are appropriate whenever the characteristics of the input path must be constant, e.g. because:
Interfering signal contributions originating from the receiver (noise, nonlinear contributions) must not change during the measurement.
A large interfering signal in the vicinity of the measured signal must not overdrive the receiver.
[SENSe<Ch>:]LOMeasure [SENSe<Ch>:]LOReference [SENSe<Ch>:]FREQuency:STARt? [SENSe<Ch>:]FREQuency:STOP? [SENSe<Ch>:]SWEep:CW|FIXed? [SENSe<Ch>:]CORRection:POWer[:STATe] [SENSe<Ch>:]POWer:ATTenuation [SENSe<Ch>:]POWer:IFGain:MEASure [SENSe<Ch>:]POWer:IFGain:REFerence
In the Source and Receiver sections of the Port Configuration table, it is possible to convert the source and receiver frequency ranges (for frequency sweeps) or CW frequencies (for power, time and CW Mode sweeps) in order to perform measurements on frequency-converting DUTs. The source frequency is port-specific whereas the receiver frequency must be the same at all ports.
Test ports 1 and 2 and test ports 3 and 4 are supplied by a common generator (see block diagrams in the data sheet). If the RF signal is simultaneously fed to two coupled ports (i.e. if Gen is switched on so that at least one signal source is permanent), the port frequencies must be the same. For normal measurements (Gen switched off), this restriction does not apply because there is only one source port per partial measurement. The frequency formula for a permanent signal source is also used for the second (coupled) test port.
The port frequencies are calculated as a multiple of the stimulus frequency fb plus an offset. The coefficients of the linear transformation between fb and the port frequencies are entered in dialogs of the following type:
Relation between channel frequency and port frequencies
The stimulus frequency fb is defined by the following sweep settings:
For a frequency sweep or segmented frequency sweep, the channel frequency is equal to the stimulus range.
For a power, time or CW Mode sweep, the channel frequency is equal to the fixed CW Frequency.
This linear frequency conversion formula has been modeled according to the needs of a typical frequency-converting measurement where mixer products and harmonics occur (see also the special Mixer Modeand Harmonic Distortionmeasurements). The port frequencies f (source frequency fsor receiver frequency for the reference channel and the measurement channel fra/frb) are related to the stimulus frequency as follows:
k and m must be integer numbers, l and n nonzero positive integers. c must a multiple of 1 Hz. Moreover the total port frequency is rounded to an integer Hz-value.
Use the Stimulus dialog to change all port frequencies based on an arbitrary reference frequency.
SOURce<Ch>:FREQuency<Pt>:CONVersion:ARBitrary:IFRequency SOURce<Ch>:FREQuency<Pt>:CONVersion:ARBitrary:EFRequency<Gen> [SENSe<Ch>:]FREQuency:CONVersion:ARBitrary [SENSe<Ch>:]FREQuency:CONVersion:ARBitrary:PMETer<Meter>
The Converter Port <n> Frequency dialog defines the frequency axis for the source power calibration; it does not actually affect the converter output frequency. The dialog is similar to the Port <n> Frequency dialog (for network analyzer ports). It can be opened from the Source section of the Port Configuration dialog if a frequency converter test setup is active.
For more information and an example refer to section Power and Frequency Settings.
SOURce<Ch>:FREQuency<Pt>:CONVersion:ARBitrary:CFRequency
The Port <n> Power dialog defines port-specific power settings. The exact meaning of the settings depends on the context from where the dialog was opened:
If opened from the Source section of the Port Configuration dialog, Port <n> Power defines the port-specific source power (with option R&S ZVA-K4). This is either a power range (for power sweeps) or a fixed power (for frequency and CW sweeps). The general purpose of the port power settings is to ensure a definite signal power at the input of the DUT, considering all possible sources of power variations in the test setup.
If opened from the Source Power Cal – Modify Source Power Cal Settings dialog, Port <n> Power defines the target power for the source power calibration.
The port-specific source power can be set to either the channel base power pb plus an offset or to a constant value. The coefficients of the linear relation between pb and the actual source power are entered in a dialog.
The Port <n> Power settings serve different purposes:
Port Power Offset defines a port-specific offset to the channel power, to be added to the step attenuator settings. The actual output power at the port is equal to the channel power Pb (Channel – Stimulus – Power) plus the Port Power Offset minus the Attenuator setting. It is equal to the Port Power Offset (in dBm) minus the Attenuator setting if 0 dBm is selected instead of Pb. For power sweep and the selection Pb, the actual port power varies across the sweep, for other configurations the port power is constant.
Attenuator defines the source step attenuator setting (with options R&S ZVABxx-B21); see Step Attenuators. If Auto is selected, the step attenuator is set such that it doesn't have to be switched over the entire sweep. The input field is unavailable and shows 0 dB if no generator step attenuator is installed.
Cal Power Offset is relevant for source power calibrations; see background information below. The parameter specifies a gain (positive values) or an attenuation (negative values) in the signal path between the source port and the calibrated reference plane. With a Cal Power Offset of n dB, the target power at the reference plane is equal to the actual output power at the port plus n dB. The Cal Power Offset has no impact on the source power.
Port <n> Power Result is the power at the reference plane of the power calibration (if available), considering all dialog settings, including the Cal Power Offset.
Use of an amplifier in the signal path
Assume that a DUT requires a constant input power of +35 dBm, and that the measurement path contains an amplifier with a 30 dB gain.
After a reset of the analyzer the channel power Pb is zero dBm. With a Port Power Offset of +5 dB at the calibrated source port and a Cal Power Offset of +30 dB, the source power calibration ensures that the constant input power of +35 dBm is maintained across the entire sweep range. The actual output power of the analyzer is +5 dBm.
Note that a power calibration with an appropriate Cal Power Offset will automatically prevent excess input levels at the DUT.
Relation between channel power and port powers
The actual output power at the ports (source power ps) is related to the channel power pb as follows:
ps = pb + c + <Slope> * f , if the pb radio button is selected ps = pb + <Slope> * f , if the 0 dBm radio button is selected
In the formulas above, f denotes the (current) source port frequency, c is the offset value entered in the Port <nr> Source Power dialog minus the Attenuator setting. The Slope parameter is set in the Sourcesection of the Port Configuration table.
Use the Stimulus dialog to change all port powers based on an arbitrary reference power. Use the ...Port Power Limits in the System Configuration – Power tab if you want to limit the source power at a physical port permanently.
The analyzer generates a warning if the power settings for one of the ports exceed the hardware limits. At the same time, bit no. 14 in the ...INTegrity:HARDware status register is set. Reduce or increase the power result until the warning disappears.
SOURce<Ch>:POWer[:LEVel][:IMMediate]:OFFSet <numeric_value>, ONLY | CPAD SOURce<Ch>:POWer<Pt>:GENerator<Gen>:OFFSet <numeric_value>, ONLY | CPAD SOURce<Ch>:POWer<Pt>:CORRection:LEVel:OFFSet (for Cal Power Offset) SOURce<Ch>:POWer<Pt>:CORRection:GENerator<Gen>:LEVel:OFFSet (for Cal Power Offset)
The Converter Port <n> Power dialog defines the port-specific source power for frequency converter ports. The dialog is similar to the Port <n> Power dialog (for network analyzer ports). It can be opened from the Source section of the Port Configuration dialog if a frequency converter test setup is active. The general purpose of the port power settings is to ensure a definite signal power at the input of the DUT, considering all possible sources of power variations in the test setup.
The Converter Port <n> Power settings serve different purposes:
The block diagram in the left-hand part of the dialog symbolizes the NWA test port providing the converter input signals RF IN, including the signal source, a continuously adjustable attenuator providing the test port power offset, and the source step attenuator (if fitted). The test port signal is configured in the Port <n> Power dialog; the current output power result for the physical analyzer port is displayed below the block diagram.
Power Transfer opens a dialog to configure an advanced power transfer model for the converter output power. This dialog is not needed for standard applications. The power transfer settings must be set in accordance with the converter properties. The resulting attenuation factor (in dB) and RF output signal power at the converter port is displayed below the Power Transfer button.
Port Power Offset and Cal Power Offset are analogous to the parameters in the Port <n> Power dialog (included in the Port <n> Power Result), however, the test port and converter values can be set independently. Depending on the Power Transfer settings, the Port Power Offset for converters with electronic attenuators will either modify the analyzer power, the electronic attenuator of the converter, or both. The Cal Power Offset makes it possible e.g. to account for a second amplifier between the converter port and the DUT.
Converter Port <n> Power Result is the power at the reference plane of the power calibration (if available), considering all dialog settings, including the Cal Power Offset.
SOURce<Ch>:POWer<Pt>:CONVerter:OFFSet
The Power Transfer dialog configures an advanced power transfer model for the converter output power at a specific port. The dialog can be opened via Channel – Mode – Port Configuration – Source Power – Converter Port <n> Power if a frequency converter test setup is active.
The Advanced Model parameters in the upper part of the dialog correspond to the general power transfer model settings in the System Configuration dialog (see Power Transfer Modes). In contrast to the System Configuration settings, the settings in the Power Transfer dialog are port-specific and reset on System – Preset. Changing the general settings overwrites the port-specific settings, however, changing a port-specific Advanced Model parameter leaves the general settings unchanged.
The parameters in the Linear Approximation panel configure the advanced power transfer mode with linear approximation of the relation between the input power PRF IN at the converter's RF IN connector and the output power PTP at the converter test port.
Output Power at Test Port defines the two parameters of the assumed linear relation between PRF IN and PTP; see figure below.
Waveguide Attenuator – Mechanical defines a fixed, frequency-independent waveguide attenuation factor which the analyzer will compensate for by increasing its RF output power. The setting is suitable for frequency converters without electronic attenuators which are equipped with an output power adjustment screw; see background information below. It allows you to vary the ratio between the RF input power and the converter output power, e.g. in order measure power-sensitive DUTs while maintaining a sufficient input power at RF IN.
The output power of frequency converters with electronic attenuators can be varied by means of RF input power (i.e. the source power at the analyzer test port providing the signal fed to RF IN) and/or by means of the electronic waveguide attenuators in the converters. A combination of both methods will generally provide an RF output signal with optimum characteristics; see Power Transfer Modes). The Waveguide Attenuator – Electronic parameters define which amount of the power variation is controlled by the electronic waveguide attenuators. In the figure below, the green area corresponds the test port power range where the electronic attenuator is used. The output power threshold PTHR ("...output power is decreased below <PTHR> dBm...") defines the right border of the area. The selected percentage ("...% of power reduction...") due to the electronic attenuator defines the slope of the green curve in the shaded area relative to the original slope (the larger the percentage, the steeper the curve). The shaded area ends where the distance between the green curve and the original blue curve has reached the selected "maximum attenuation" of the electronic attenuator. As a result of the combination between RF and waveguide attenuation, lower converter output powers can be achieved at larger RF input powers. This improves the spectral purity of the converter output signal in the low-power range.
Recommended procedure for mechanical attenuation factors
Frequency converters like the R&S ZVA-Z110 have no electronic attenuators, however, their output power can be varied by means of a mechanical adjustment screw. The mechanical attenuation factor allows you to work with accurate output power settings for this type of converters, too. To avoid excess input powers at the converter input RF IN, it is recommended to decrease the port power of the analyzer by the desired attenuation factor (e.g. 3 dB). The procedure described below will then compensate for the power reduction and ensure a lower converter output power with a high spectral purity.
To adjust a converter no. <n> for a waveguide attenuation factor of 3 dB,
In the Port <n> Power dialog, reduce the Port Power Offset by 3 dB.
Open the converter's adjustment screw completely and measure the output power (wave quantity a<n>, measured at the analyzer port no. <n>).
Store the a<n> trace to the memory (Trace – Trace Funct – Data -> Mem).
Select the mathematical trace mode Trace – Trace Funct – Math = Data / Mem.
Slowly tighten the screw until the mathematical trace has been shifted down to –3 dB. Keep the screw at this position.
Enter +3 dB into the mechanical attenuation field in the Power Transfer dialog.
The waveguide attenuation caused by the adjustment screw is shown in the Converter Port <n> Power dialog, below the Power Transfer button. The analyzer will increase its port power, compensating for the power reduction selected in the first step. The converter's output power is reduced by 3 dB.
SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:AMODel SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:DESCription SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:SLOPe SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:OFFSet SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:ATTenuator SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:MECHanical:ATTenaution SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:ELECtronic:LIMit SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:ELECtronic:REDuction SOURce<Ch>:POWer<Pt>:CONVerter:TRANsfer:ELECtronic:MATTenuation
This dialog enables individual Automatic Level Control (ALC) settings for the physical analyzer ports. The settings are a subset of the general ALC settings, accessed via Channel – Mode – ALC (All Chans).
The port-specific ALC settings overwrite the general ALC settings. E.g. with active ACL (All Chans), you can select Individual Settings for Physical Port 1 and uncheck ALC On. This disables the ALC at the physical analyzer port no. 1. The ALC at all other ports is still enabled.
SOURce<Ch>:POWer<Pt>:ALC:CONTrol SOURce<Ch>:POWer<Pt>:ALC[:STATe] SOURce<Ch>:POWer<Pt>:ALC:PIParameter SOURce<Ch>:POWer<Pt>:ALC:PIParameter:GAIN SOURce<Ch>:POWer<Pt>:ALC:PIParameter:ITIMe SOURce<Ch>:POWer<Pt>:ALC:CLAMp
This dialog customizes the Port Configuration table and displays or hides columns.
(Un)checking Logical Port, Source or Receiver displays (removes) the corresponding sections in (from) the Port Configuration table.
(Un)checking one of the second-level boxes displays (removes) the corresponding column in (from) the Port Configuration table.
The physical port number is always displayed. The logical port information is displayed only if a balanced port configuration is defined.
No command, display configuration only.
The Stimulus dialog modifies all sweep frequencies and powers in the active channel, based on an arbitrary frequency and power reference. This is particularly useful in arbitrary mode (with option R&S ZVA-K4), where the frequencies and source powers at the ports are independent. The dialog is accessed from the Port Configuration dialog.
The Stimulus dialog can be opened from the context menu of the channel list.
The available sweep parameters depend on the Current Sweep Type (Channel – Sweep – Sweep Type) which is displayed below the title bar of the dialog.
Sweep Type
Frequency parameters
Power parameters
Lin. Frequency Log. Frequency
Start Stop
CW
Segmented Frequency
– (defined by the sweep segments)
Power
Time CW Mode
The frequencies and powers are displayed in two separate but analogous panels:
Enter & Display in the Frequency panel contains a list of the channel base frequency fb plus the source and receiver frequencies at all logical ports that depend on fb. The list includes the frequencies of external power meters and generators. Fixed source and receiver frequencies (see Converted Frequencies) are not in the list; they are not affected by the settings in the Stimulus dialog. For R&S ZVA analyzers without option R&S ZVA-K4, all frequencies and powers are coupled so that this selection has no effect.
Enter & Display in the Power panel contains a list of the channel base power pb plus the source and receiver powers at all logical ports that depend on pb. The list includes the powers of external power meters and generators. Fixed source and receiver powers (see Port-Specific Power) are not in the list; they are not affected by the settings in the Stimulus dialog. The selected stimulus axis appears in the channel list when the Port Configuration dialog is closed, e.g. Base Pwr. x dBm, Port 1 Pwr x dBm, Gen1 Pwr x dBm.
Start, Stop define the frequency/power sweep ranges; CW defines the fixed frequency/power.
Frequency and power definition in the Stimulus dialog
If the selected reference frequency or reference power is changed, the analyzer modifies all source and receiver frequencies/powers accordingly, leaving the frequency and power conversion formulas unchanged. The Stimulus dialog thus ensures that all system frequencies/powers can be modified consistently, based on an arbitrary reference frequency.
The power and frequency entries in the Stimulus dialog are unrestricted. A compatibility check is performed when the dialog is closed. Frequencies and powers beyond the analyzer's hardware limits are marked with a red input field in the calling Port Configuration dialog.
By default, all port frequencies/powers are referenced to the base frequency/power (Channel Base fb/Pb). If another port frequency or power, which was selected as a reference, becomes invalid (e.g. because it is set to a constant value), it is automatically replaced by the channel base frequency/power.
[SENSe<Ch>:]SWEep:AXIS:FREQuency [SENSe<Ch>:]SWEep:AXIS:POWer