R&S®ZVR-K9 Operating Manual
Test and
Measurement Division
Software Manual
Virtual Embedding Networks
ZVR-K9
1106.8830.02
Printed in the Federal
Republic of Germany
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ZVR-K9
Contents
Contents
Basics ..................................................................................................................................................... 1
Measuring Tasks ........................................................................................................................ 1
Approach .................................................................................................................................... 2
System Requirements...................................................................................................................... 3
Installation ............................................................................................................................................ 4
Getting Started .................................................................................................................................... 5
Preparation ................................................................................................................................. 5
Importing a File Generated by a CAD Program.......................................................................... 5
Storing the Calibration ................................................................................................................ 5
Including a Network in a Calibration ........................................................................................... 6
Result.......................................................................................................................................... 6
Menu Overview ................................................................................................................................... 7
File
......................................................................................................................................... 7
Measure Network ..................................................................................................................... 14
Embedding................................................................................................................................ 19
De-Embedding.......................................................................................................................... 20
Cal Manager ............................................................................................................................. 20
Info
....................................................................................................................................... 21
Application Examples .................................................................................................................... 22
Embedding: Testing SMD Components with a Virtual Matching Network................................ 22
De-Embedding: Measurement of “Embedded“ Components ................................................... 23
Measuring a Microstrip Transition ............................................................................................ 24
Index ...................................................................................................................................................... I.1
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Figures
ZVR-K9
List of Figures
Fig. 1:
Fig. 2:
Fig. 3:
Fig. 4:
Fig. 5:
Fig. 6:
Inner and outer ports of a transformation network ........................................................................ 1
Virtual impedance matching.......................................................................................................... 1
Reducing the de-embedding problem to the embedding problem ................................................ 2
Scattering parameters of virtual network getstart.......................................................................... 6
Numbering of the ports of the transformation network.................................................................. 8
Virtual transformation network seen as the “difference“ between a test fixture with and a test
fixture without matching network ................................................................................................. 22
Fig. 7: Calibration standards for measuring a transition
from printed circuit board to ceramic substrate........................................................................... 24
Fig. 8: S-parameters of a transition from PCB to ceramic substrate ..................................................... 25
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ZVR-K9
Basics
Basics
Measuring Tasks
A frequently occurring category of measuring tasks in network analysis comprises the so-called
embedding and de-embedding problems. A device under test (DUT) is embedded if its ports are all
connected to a transformation network (TN) so that only the ports of the transformation network are
accessible from outside. This transformation network may be e.g. a matching circuit, a test fixture or a
case. In general, it features twice as many ports as the DUT. The ports of the transformation network
which are connected to the device under test are referred to as “inner“ ports, those accessible from
outside as “outer“ ports. Fig. 1 shows an example of a two-port embedded in a transformation network
with four ports.
TN
DUT
inner
outer
Ports of the TN
Fig. 1:
Inner and outer ports of a transformation network
One possible measuring task consists of measuring the really existing DUT such as if it were embedded
in a transformation network, although the latter is physically not existing. In this case, virtual embedding
is involved. Fig. 2 shows the example of a measurement of a DUT with the input and output impedance
Z1, which is provided with virtual impedance transformers from Z1 to Z0 and is thus matched to the
reference impedance Z0 for the measurement.
NWA
(reference impedance Z0)
1
DUT
Z0
Z1
Z1
Z0
virtual impedance transformers Z0 : Z1
Fig. 2:
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Basics
ZVR-K9
In the opposite case, the device under test is inseparably connected with the transformation network, i.e.
the ports of the DUT are not accessible. If, nevertheless, the S-parameters of the DUT alone are to be
determined, a “de-embedding“ problem is involved. This measuring problem can be reduced to the
embedding problem by embedding the real combination of DUT and transformation network into the
virtual inverse transformation network. The inverse and the real transformation network cancel each
other so that, viewed from outside, only the DUT is left (Fig. 3).
TN-1(virtual)
TN (real)
DUT
Fig. 3:
Reducing the de-embedding problem to the embedding problem
A third type of measuring task consists of the determination of the S-parameters of an unknown, but
physically existing transformation network. In the case of the two-port measurement, the difficulty is
based on the fact that the network is a four-port and, therefore, cannot directly be measured. Also the
inner and outer ports often differ in the type of transmission line (e.g. in the case of a test fixture for
SMD components), which makes the calibration for a direct measurement more difficult. Measuring
tasks like that are often referred to as Unterminating problems.
Approach
The solution to embedding and de-embedding problems known so far consists of importing the Sparameters of the really existing DUT measured with a network analyzer into a CAD program and
embedding them there in a simulated circuit environment. In addition to the network analyzer, a
controller on which the CAD program runs is generally required. The data transmission is in most cases
effected via IEC bus. This procedure can hardly be performed in automatic mode, since each simulation
requires manual user operations. Due to the data transmission and computing times, a real-time
indication, e.g. for adjustment of the DUT, is not possible.
In this case, the Software Option ZVR-K9 of the Network Analyzer ZVR offers clear advantages. The
idea is to consider the virtual transformation network in the system error correction data of the network
analyzer. Since a system error correction is performed anyway for almost all measuring tasks, no
additional stage of processing is required. Besides, there is no data transmission to an external
controller. Thus, the measurement with a virtual transformation network is as fast as the measurement
without one, real-time adjustment of the DUT is possible.
The S-parameters of the transformation network originate either from a CAD program or from a
measurement. The transformation network is not directly measured, but by forming the difference
between calibrations at the inner and outer ports. This avoids the through-connection between ports of
different types of transmission lines which would be required in the calibration for a direct measurement.
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ZVR-K9
System Requirements
System Requirements
In order to use all features of the software option ZVR-K9, Virtual Embedding Networks, a Network
Analyzer ZVR, ZVC ZVM or ZVK is required. This manual only refers to the model ZVR, however, all
that is said also applies to ZVC, ZVM and ZVK. ZVR-K9 version 2.1 runs under Microsoft Windows 3.1
or NT 4.0, for version 3.1 Windows NT 4.0 is required. On older instruments ZVR with stock no.
1043.0009.xx and ZVC with stock no. 1106.9020.xx, Windows 3.1 is part of the option ZVR-B15
(Controller). Connection of an external keyboard to the ZVR is necessary, a mouse considerably
facilitates operation as with all Windows applications. For Windows 3.1, the version number of the ZVR
firmware must be 1.70 or higher, for Windows NT it must be 3.04 or higher. The version number can be
polled via INFO: FIRMWARE VERSIONS.
If one ist only interested in the functions of the File menu, that is import, export and administration of
transformation networks, one may, as well, install ZVR-K9 version 3.1 on a PC under Windows
95/98/NT4.0.
Important Note:
If ZVR-K9 runs under Windows 3.1, the files
D:\RUNTIME\RSIB\RSlB.DLL and
D:\RUNTIME\RSIB\RSDDE.DLL
must be copied to the directory
C:\WINDOWS\SYSTEM
before starting the application for the first time!
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Installation
ZVR-K9
Installation
The software option ZVR-K9 is supplied on two installation disks. For an installation on a ZVR, the key
code number, which can be found on the sheet “software installation”, is additionally required. You may
also obtain this number from your R&S representative.
1. (only for installation on a ZVR) Enter the key sequence SETUP: OPTIONS: ENABLE NEW OPTION
on the ZVR. The input field for optional key codes will then be opened. Enter the key code number
for the option ZVR-K9. If the input is correct, the message “OPTION KEY OK“ will appear, otherwise
"OPTION KEY INVALID“.
2. (only for installation on a ZVR) Switch the ZVR from measurement screen to PC screen by
simultaneously pressing the keys Alt and Sys Rq on the external keyboard.
3. Insert installation disk no. 1 into the disk drive.
Windows 3.1 (only in the case of installation on a ZVR):
4. Start Windows by entering WIN.
5. Select the command Run from the File menu in the Windows program manager.
6. Enter the following text in the command line:
a:\setup
Windows NT:
4. Select the command Run from the Windows Start menu.
5. Enter the following text in the Open field:
a:\setup
7. Select OK.
8. Follow the instructions on the screen.
The Setup program automatically creates all the necessary directories. You may determine the name of
the program group for ZVR-K9 and the de-installation program. After the installation has been
terminated, this program group is in the foreground.
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ZVR-K9
Getting Started
Getting Started
For installation of the Software ZVR-K9, a virtual transformation network generated with the aid of a
CAD program is included. This network permits to illustrate some of the numerous possible applications
of this software option.
Preparation
Reset the ZVR to a predefined default status using PRESET and perform a full two-port user calibration
according to the TOM method over the complete frequency range. After calibration, establish a throughconnection (THROUGH) between the test ports PORT 1 and PORT 2. Use the key combination Alt +
Sys Rq to switch over to PC operation and start Windows. Then start the application ZVR-K9 in the
program group with the same name.
First, only the main menu and the status line are visible at the lower edge of the screen. The left-hand
field of the status line displays the currently active input function or the current action of the program, the
right-hand field indicates the user prompts.
Importing a File Generated by a CAD Program
The demo network is provided in the data base format of Ansoft (e.g. Serenade) under the name
GETSTART in the directory c:\rsapplic\demo. To be able to use it, import and save it in the specific data
format of the Software ZVR-K9. For this purpose, use the command Import Network in the File menu. It
opens a window having the same name. Within the frame Select File on the left-hand side, select the file
GETSTART.FLP. Then click on the box TN1 THROUGH in the graph. The box will turn red and the
frame Select Action will appear below. In the frame, select Insert Selected File. Now the format of the
import file will be checked. The following question may be answered by YES or NO, since the right
subnetwork TN2 of GETSTART.FLP is just an ideal through, too. Now the box TN1 displays the file
name instead of THROUGH. Click on Import Network(s). Then follows the window Save Transformation
Network for entering the name of the network and an optional comment with up to 256 characters. The
Network List indicates all networks stored so far for info. By clicking on OK, the new network file will be
stored in the ZVR-K9 format, thus completing the file import.
Storing the Calibration
Next, the imported network is to be considered in the previously created user calibration, i.e. the latter is
modified. It is recommended to store the original calibration status if you intend to reuse it later. For the
management of calibration data, the command Cal Manager is provided in the main menu, calling up an
interactive window. The keypad Append Active Cal to List permits to store the currently active user
calibration in the Cal List. You may define a name with a length of up to 8 characters for this calibration.
Vice versa, a calibration can be reactivated from the Cal List via Set Cal Active. In addition, the Cal
Manager permits you to determine in which calibration (Base Cal) a network is to be considered. The
current setting is indicated on the left side in the frame Base Cal for (De-) Embedding. You may define
either the current calibration or the one selected in the Cal List as Base Cal. Even if you have
transferred the previously created user calibration into the Cal List, it remains active and you may
maintain the default setting of the frame Base Cal for De-(Embedding). The key Close permits to leave
the Cal Manager.
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Getting Started
ZVR-K9
Including a Network in a Calibration
Call up the command Embedding in the main menu. The window displayed shows you the frame Base
Cal with the base calibration set in the Cal Manager, into which the network is embedded. The Network
List in the lower half of the screen lists all currently stored networks. Next to the name, you can see the
most important data at a glance, such as date, comment, point grid and frequency range. If the list
contains many entries, you will be able find the desired network faster with these additional pieces of
information. If you have installed the Software ZVR-K9 and performed all steps described so far, the
network list only contains the previously imported getstart. Select this network by clicking on the relevant
line. The name will then appear in the frame Embedding Network and the key Modify Base Cal can be
operated. Click on this key. After successful termination of embedding an appropriate message will
appear. Confirm this message and return to the main menu.
Result
You may have noticed in the last step that the status LED REM(OTE) was switched on as long as the
window Embedding was open. This LED indicates that the ZVR is under the control of the Software
ZVR-K9. In the main menu, however, this LED is always switched off. You may then switch over to
measurement screen and operate the ZVR via the front panel. Switch to measurement screen now and
activate the four-channel display (DISPLAY: QUAD CHAN QUAD SPLIT). You will then see all the four
S-parameters of your device under test - the through-connection - as if it were embedded into a virtual
network. This virtual network consists of an ideal bandpass filter at PORT 1 and an ideal throughconnection at PORT 2. Thus, only the S-parameters of the bandpass filter with a passband of 1.2 to 1.5
GHz take effect (Fig. 4).
Fig. 4:
Scattering parameters of virtual network getstart
When the base calibration is modified, frequency range and point grid of the virtual network are adopted.
This is why the frequency range has also changed compared with the previous status after PRESET.
Further important functions are the measurement of a transformation network and the data export in
CAD file format. This will be explained in more detail in the sections "Menu Overview" or "Application
Examples".
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Menu Overview
Menu Overview
In this section, all functions are listed according to their order in the main menu.
When a command is called up from the main menu, the network analyzer changes to the REMOTE
status. Thus only in the main menu can the ZVR be operated via the front panel after switchover to the
measurement screen by means of the key combination Alt + Sys Rq.
Attention: This Windows application controls the ZVR via the DDE interface. This is
why the network analyzer can not be controlled via IEC/IEEE-bus while
ZVR-K9 is active.
File
This command opens a submenu containing the functions for the data transfer between ZVR-K9 and
CAD programs as well as for the management of transformation networks. Furthermore, the system
configuration (hardware platform) may be defined here. The Software ZVR-K9 can also be left via File.
This menu is available even when ZVR-K9 has been installed on a PC.
Import File
The function Import File permits to import files which contain the S-parameters of virtual networks in the
data format of CAD programs. This function can be used e.g. to design ideal transformation networks in
a CAD program and import their S-parameters as a network. Likewise, it is possible to export a
measured network, process it in a CAD program and import the modified network back to the Software
ZVR-K9.
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Menu Overview
ZVR-K9
Supported are the data base formats of Ansoft/Compact Software (e.g. Super Compact, Serenade)
with the file name extension .flp and of Agilent EESof EDA (Touchstone, Series IV, ADS) with the
extension .s4p. An example of the flp.format is the file getstart.flp in the directory c:\rsapplic\demo.
When importing the S-parameters of a transformation network, the correct definition of the port numbers
is crucial. For four-ports numbering is sequential from left to right (Fig. 5)
PORT 1
Fig. 5:
1
TN1
2
3
DUT
TN2
4
PORT 2
Numbering of the ports of the transformation network
Caution:
It is very important to observe the assignment of the ports in order to avoid
faulty results.
A possible coupling of the sub-two-ports TN1 and TN2 is not taken into account, i.e. the upper right and
the lower left (2x2) sub-matrix of the four-port S-matrix is taken to be zero. To avoid singularities, the
four-port S-parameters S12 and S43 must be different from zero, i.e. the two-ports TN1 and TN2 transmit
in at least one direction.
Alternatively, one may compose the transformation network of two different two-port files. In this case,
port 1 of TN1 and TN2 is always oriented towards the device under test, which requires the parameter
S21 to be different from zero. Furthermore, it is also possible to import a sub-two-port of a four-port.
In addition, one-port reflection factors may be imported as well. The reflection factor is interpreted as S11
and S22 of a symmetric two-port, which has an ideal transmission factor equal to 1.
Before completing the import of the transformation network one may modify its sub-two-ports. A two-port
may be turned to reverse orientation or replaced by an ideal through-connection.
The point grids of the files to be imported must be either linear or logarithmic and must coincide for the
two sub-two-ports. The reference impedances of the sub-two-ports must be identical, too. Besides, for
files in the Ansoft format, it is checked whether the point grid data in the file header is consistent with the
actual data set in the file body.
All complex data formats supported by the aforementioned CAD programs are recognized. These are
magnitude and phase, magnitude in dB and phase as well as real and imaginary part. Permissible units
for frequency indications are Hz, kHz, MHz and GHz.
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ZVR-K9
Menu Overview
Detailed procedure:
Window Import Network:
The frame Select File enables one to select path and name of the file to be imported. Only files with the
extension .flp (Ansoft format) or .snp (Agilent-EESof format, n = 1, 2 or 4) are displayed. A
transformation network is always a four-port that consists of the two sub-two-ports TN1 and TN2. These
two-ports can be configured independently. This is accomplished by clicking on either box TN1 or TN2,
which makes the selected box turn red and opens the frame Select Action. TN1 and TN2 are predefined as through-connections, in this case only the keypad Insert Selected File is available. Clicking
on it, the format of the file selected in the frame Select File is examined. After this check has been
passed, the name of the selected file, instead of THROUGH, appears in the box. Otherwise, a message
box indicates which error has been found in the format.
If a four-port is to be imported, one may click on either of TN1 or TN2. The user is prompted to decide
whether the complete four-port should be read or just the selected sub-two-port.
After having pre-selected a file, the other two keypads in the frame Select Action will become available,
too. Replace by Ideal Through Connection restores the original state, i.e. an ideal through connection is
assumed for the selected two-port. Interchange Ports interchanges port 1 and port 2 of the two-port,
which means that S11 and S22, as well as S12 and S21, swap their places in the S-matrix. In the graph the
port numbers are interchanged.
The sub-two-ports TN1 and TN2 may be modified as often as desired. When the final configuration has
been found, the actual file import is started via the keypad Import Network(s). The progress of the three
calculation steps that are performed is indicated by a bar in the status area.
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Menu Overview
ZVR-K9
The next window that follows is Save Transformation Network:
The field Name permits to specify the name under which the imported data are stored as a virtual
network. This name must comply with the DOS convention for file names, but it features no extension.
No differentiation is made between upper-case and lower-case letters. The Network List lists all
networks stored so far. The field Comment permits to enter an optional comment consisting of up to 256
characters. This additional information will then appear in the detailed network list under the command
Embedding. The keypad OK completes the file import.
Export Network
The function Export Network is used to output the S-parameters of virtual networks in an ASCII data
format which can be imported by CAD programs. Supported are the data base formats of
Ansoft/Compact Software (e.g. Super Compact, Serenade) with the file name extension .flp and of
Agilent-EESof (Touchstone, Series IV, ADS) ) with the extension .snp (n = 2 or 4). This function
permits e.g. to import measured transformation networks into a CAD program for analysis or
modification.
One may either export the complete transformation network as a four-port or one of the sub-two-ports.
Anyway, the port numbering described under Import Network holds.
The computation of the transformation networks is based on the 7-term calibration techniques where the
four transmission parameters of the sub-two-ports are normalized. The normalization causes the values
of the individual transmission coefficients of TN1 and TN2 to be changed. The calculation of the Sparameters of an embedded device under test remains unaffected by this normalization, since for this
only the products of transmission parameters, which are invariant with respect to normalization, are
used, If one knows that one of the two sub-two-ports is reciprocal, its transmission parameters can be
adequately unnormalized for export. If both are reciprocal, it is sufficient to define one side as reciprocal,
the other side will then also be correctly exported.
For exporting the networks, all data formats supported by the CAD programs mentioned above are
offered.
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ZVR-K9
Menu Overview
Detailed procedure:
Window Export Network:
The Network List lists all networks stored. Set the selection bar to the network to be exported and select
the keypad Export Network.
Window Select Export File Options:
This window is used to determine the options for data export. Within the frame Export Subnetwork, one
can decide whether the complete transformation network is to be exported or just a sub-two-port. The
frame Reciprocal Subnetwork allows the user to determine whether and how the unnormalization of the
transmission parameters shall be performed. The frame File Format permits one to choose either the
Ansoft (formerly: Compact Software) or the Agilent-EESof format. The output format for the complex Sparameters is selected in the frame Complex Data Format. It is possible to choose between magnitude
and phase, logarithmic magnitude (in units of dB) and phase as well as real and imaginary part. Finally,
the frequency unit can be selected in the frame Frequency Unit. Here, the possible units are GHz, MHz,
kHz and Hz. Having defined all options select the keypad Save Export File.
The frequency values and S-parameters are stored with an accuracy of 7 digits after the decimal point.
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Menu Overview
ZVR-K9
Window Save Export File:
This window is used to determine the path and the name of the file to be exported. According to the data
format selected before, a file name extension is determined automatically. Save starts the storage
procedure. Its successful termination is indicated by a message that is to be confirmed by the user.
Network Manager
The window Network Manager is used for the management of transformation networks.
Transformation networks can be renamed, deleted or loaded from the ZVR into the controlling
computer. The Network List on the left lists all stored networks. The desired network can be selected
using the selection bar. To rename a network press the keypad Rename, which will open a field for
entering the new name. Network names must comply with the DOS convention for file names, but do
not contain any extension. The keypad Delete deletes the selected network. For the LAN Configuration
(see Window Hardware Configuration), the keypad Load Networks from NWA is available, too. It opens
a window having the same name.
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ZVR-K9
Menu Overview
This window is useful for copying transformation networks from the ZVR to the controlling computer.
The NWA Network List shows the networks that are stored in the ZVR, choose those which are to be
copied by means of a selection bar. Select All selects the whole list. Load Selected Networks loads all
selected networks into the controlling computer. The window is closed via Close.
Hardware Configuration:
The window Hardware Configuration allows the user to specify the hardware platform for the software
ZVR-K9:
If the software ZVR-K9 runs on a ZVR under Windows NT, choose Stand-alone Network Analyzer.
ZVR-K9 can also be run on a Windows PC, in this case the option Stand-alone MS Windows Computer
must be selected. For this configuration, however, the main menu contains only the File and Info
submenus, thus only transformation network management functions are available.
If the ZVR is connected to a computer network via an Ethernet adapter (option FSE-B16), the ZVR-K9
software may also be started from any Windows computer in the network. In this case, choose the LAN
Configuration option, then all functions of ZVR stand-alone operation are available. Enter the IP address
of the ZVR into the IP Address field using the format 12.34.56.78. Note that calibration data (Cal List)
are always related to the network analyzer and thus kept in it, whereas transformation networks
(Network List) are stored in the controlling computer. If there are transformation networks on the ZVR,
they may be copied to the controlling computer by means of the function Load Networks from NWA (see
Network Manager). A special case of the LAN Configuration should be mentioned, which is stand-alone
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Menu Overview
ZVR-K9
operation of a ZVR. In this case, ZVR-K9 running on the network analyzer controls the analyzer via ist
own IP address.
As long as the Hardware Configuration window is open, configuration changes do not yet become
effective. It is the Change Configuration keypad that accepts the selected configuration and quits the
window. If no change is desired, one may return to the main menu via the keypad Exit without change.
Exit
The command Exit terminates the Software ZVR-K9.
Measure Network
This command can be used to measure transformation networks (Unterminating problem). This is
particularly useful if the network to be virtually considered later is physically present (e.g. test fixture,
component case) but be designed via CAD with sufficient accuracy. The scattering parameters of the
network can be determined by carrying out a calibration at the outer and inner ports and by forming the
difference between the respective error four-ports. This procedure can be used if both the outer and the
inner ports are directly accessible.
In some cases, however, the desired transformation network is inseparably connected with an auxiliary
network. If the auxiliary network alone (e.g. a test fixture without transformation elements) is also
physically existing, a two-stage procedure permits to determine first the auxiliary network and the
auxiliary network plus transformation network and finally the transformation network itself by means of
three calibrations. This case is referred to as “indirect access“. As a prerequisite, the outer ports of
auxiliary network and auxiliary network plus transformation network must feature the same connector
type so that one common outer calibration is sufficient.
Inner and outer calibrations, on the other hand, do not necessarily refer to the same connector type. For
example, test fixtures for non-coaxial components (SMD cases etc.) with coaxial outer connectors can
also be measured. For non-coaxial inner calibrations, 7-term self-calibration techniques are
recommended, such as e.g. TRL, TRM or TNA, which do not require all standards to be completely
known.
The two partial two-ports TN1 and TN2 as well as, if applicable, the auxiliary networks AN1 (= Auxiliary
Network 1) and AN2 must be transmitting. To avoid numerical inaccuracies, the transmission loss
should not exceed 50 dB.
Detailed procedure:
Before calling up Measure Network, frequency range, point grid and other desired sweep settings for the
calibration measurements must be set via the front panel of the ZVR. The main menu permits to switch
between measurement and PC screen using the key combination Alt + Sys Rq.
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ZVR-K9
Menu Overview
Window Access to Transformation Network
(called up by the command Measure Network in the main menu):
This window permits to determine whether the transformation network to be measured is directly
accessible (keypad Direct) or connected to an auxiliary network (keypad Indirect). Both cases are
illustrated by graphs showing the reference planes for inner and outer calibration.
In the case of indirect access, the assumption is made that the transformation network is connected to
the outer ports of the combination transformation/auxiliary network. Thus it can be taken into account in
the system correction data of the NWA later. As all this represents only a model, it is irrelevant whether
the real transformation and auxiliary networks are actually connected in series as described above.
Window Direct Measurement
(called up via keypad Direct in the window Access to Transformation Network):
This window permits to start inner (keypad Inner Cal) and outer calibration (keypad Outer Cal) as well as
the final computation of the transformation network. The order of inner and outer calibration is arbitrary.
The keypad Calculate Transformation Network, however, can only be operated after both calibrations
have been performed. The BACK button leads back to the previous window. This button is also
available in most of the windows described in the remainder of this section. Within the Measure Network
menu, the order in which the windows are called up is stored, so it is possible to return to the previous
windows by pressing the BACK button repeatedly.
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Menu Overview
ZVR-K9
Window Direct Inner Calibration: Cal Source
(called up via keypad Inner Cal in the window Direct Measurement):
This window permits the user to choose between using the currently active calibration of the ZVR as
inner calibration (keypad Use Active Calibration) and performing a new calibration (keypad Start New
Calibration). If you select the currently active calibration, this is restored with the original sweep settings
valid when this calibration was performed. The same is true if the calibration was switched off. Thus,
point grid, generator level, internal/external operating mode, etc. may change. If an outer calibration
already exists, it becomes invalid. These sometimes undesired results of the function Use Active
Calibration are indicated in a message window which is to be confirmed by the user and from where the
function can be aborted.
Window Inner Calibration: Define Connector and Cal Method
(called up via keypad Start New Calibration in the window Inner Calibration):
This window permits to determine connector type and sex of the test ports as well as the calibration
method for the inner calibration. When the ZVR is operated via the front panel, these parameters are
polled in successive menus. One of the four 7-term techniques (Txx) implemented in the ZVR can be
selected as a calibration method. The keypad Measure Calibration Standards can only be operated
when the necessary entries have been made.
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ZVR-K9
Menu Overview
Window Direct Inner Calibration: Txx
(called up via keypad Measure Calibration Standards in the window Inner Calibration: Define Connector
and Cal Method):
These windows correspond to the calibration measurement menus for 7-term techniques with ZVR
operation via the front panel. The softkeys for measuring the standards are simulated by keypads in
terms of labeling and functions. By actuating a keypad, the calibration sweep is triggered; when it is
finished, the key turns green. All standards can be measured in any order and as often as desired.
While the individual standards are measured, a plausibility check is performed. A message window pops
up if any of the measurement results appear implausible. The keypad Apply Calibration can only be
operated when the minimum number of standards have been measured. Apply Calibration permits to
return to the window Direct Measurement after computation of the correction values. A message window
appears also if the implicit verification procedure during the calculation of the correction coefficients
yields and error or if any of the standards are not defined in the current sweep range. The keypad Inner
Cal turns green to indicate that the inner calibration has been performed. If required, it can be repeated
as often as desired like the measurement of a single standard.
Window Direct Outer Calibration: Cal Source
(called up via keypad Outer Cal in the window Direct Measurement):
For the outer calibration the same is true as for the inner one. After the inner and outer calibration have
been performed, the key Calculate Transformation Network in the window Direct Measurement can be
operated.
Window Save Transformation Network
(called up via keypad Calculate Transformation Network in the window Direct Measurement):
This window is identical to the one described under File – Import. The field Name permits to determine
the name under which the imported data are stored as virtual network. This name must comply with the
DOS convention for file names and has no extension. No differentiation is made between upper-case
and lower-case letters. The Network List lists all networks stored so far. The field Comment permits to
enter an optional comment with a length of up to 256 characters. This additional information will then
appear in the detailed network list under the command Embedding.
After confirmation with OK, the difference between inner and outer calibration is formed and stored as
transformation network. A bar in the status line shows the progress of the storage procedure. After the
storage, the window Measure Network appears which permits to return to the window Direct
Measurement (page 17) via the keypad Meas Window. This may be useful if, after storage, you notice
that an error has occurred in a calibration and you want to repeat this calibration. The other keypad Main
Menu permits to return to the main menu, deleting the inner and outer calibration. In this case, the
window Active Calibration enables you to adopt the outer calibration as the active one. Actually, the
outer calibration is often identical with the one in which the network is to be considered in the following
step.
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Menu Overview
ZVR-K9
Window Indirect Measurement
(called up via keypad Indirect in the window Access to Transformation Network):
In the case of the indirect measurement of a transformation network, two physical networks are given,
namely the auxiliary network combined with the transformation network as well as the auxiliary network
alone. For example, the combination of auxiliary network and transformation network may be a test
fixture with integrated matching circuit, the auxiliary network alone a test fixture without matching circuit.
Therefore, as opposed to the direct measurement, two inner calibrations are required. The keypad Inner
Cal AN+TN starts the calibration with auxiliary and transformation network, the keypad Inner Cal AN
only starts the calibration with the auxiliary network only. In terms of key functions and test procedure,
the indirect measurement corresponds to the direct measurement.
Both for inner and outer calibrations, it is possible to select the currently active one. All other calibrations
are thus reset to the “not performed“ status, the corresponding keys turn gray.
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ZVR-K9
Menu Overview
Embedding
The command Embedding opens the Embedding window which permits to consider a virtual
transformation network in the system error correction data:
A device under test, which is measured with correction data modified like this, behaves as if it were
embedded into the transformation network. The original calibration before the modification is referred to
as base calibration. This may be either the currently active calibration or a calibration from the Cal List of
the Cal Manager. Configuration of the base calibration is also performed in the Cal Manager. The
current base calibration is indicated in the frame Base Cal.
The embedding virtual transformation network is selected from the Network List. In addition to the name
of the network, this list includes a number of other important data, such as date of storage, comment,
point grid and frequency range. These data make it easier to find a desired network. If required, the
column lines of the Network List can be shifted using the cursor, e.g. in order to make a longer comment
completely visible. If not all networks can be shown in the list, a scrollbar will appear at the right-hand
edge. A network can be selected by clicking on it with the mouse, the respective line being displayed on
colored background. The name of the currently selected virtual network is indicated in the frame
Embedding Network.
Modify Base Cal
The keypad Modify Base Cal starts the computation of the modified calibration. A bar in the status line
indicates the progress of the computation. After successful termination, a message is output, the
modified calibration is activated and the program returns to the main menu level.
The base calibration must have been performed according to a Txx technique (7 error terms).
Therefore, normalization, one-port calibration or 12-term calibration (TOSM) cannot be used.
The modified calibration features the same point grid as the virtual network. In the computation, an
interpolation is made between the sampling points of the base calibration. However, this assumes that
the base calibration completely covers the frequency range of the virtual network, i.e. extrapolation
beyond the frequency range of the base calibration is not possible.
To ensure correct calculation of the modified correction data, the S-parameters of virtual network and
base calibration must be referred to the same impedance. Otherwise, a warning will appear.
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Menu Overview
ZVR-K9
The modified correction data are only used in the active display channel unless the channels are
coupled. It is of no importance whether the base calibration was recorded with coupled or decoupled
channels.
Close
The keypad Close closes the window Embedding and allows to return to the main menu.
De-Embedding
The result of the command De-Embedding is inverse to that of the command Embedding. Whereas
Embedding permits to embed a DUT into a virtual transformation network, De-Embedding can be used
to virtually remove a physically existing network. This is achieved by considering the inverse virtual
network in the system error correction data. Of course, the scattering parameters of the network must
be known for this purpose.
For operation and procedure refer to the command Embedding.
Cal Manager
The window Cal Manager provides functions for the management of system error correction data:
System error correction data can be stored on the hard disk irrespective of the SAVE-RECALL
mechanism of the ZVR. The active correction data can be stored under a freely selectable name,
conversely, the stored data can be activated again. The files stored are displayed in the Cal List.
Correction files can be renamed or deleted. The Cal Manager also permits to determine the base
calibration to be used for embedding or de-embedding. Possible base calibrations are the active
calibration or the one marked in the Cal List.
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ZVR-K9
Menu Overview
Append Active Cal to List
The function Append Active Cal to List adds the active calibration to the Cal List. The correction data are
transferred, irrespective of whether they are permissible as base calibration for embedding or deembedding. The name may comprise up to 8 characters. The keypad Append Active Cal to List can only
be operated if an active calibration is available.
Set Cal Active
The function Set Cal Active permits to activate the calibration marked in the Cal List by means of the
selection bar. This keypad can only be operated if there are entries in the Cal List.
Rename Cal
The function Rename Cal is used to rename the calibration marked in the Cal List by means of the
selection bar. The name may comprise up to 8 characters. This keypad can only be operated if there
are entries in the Cal List.
Delete Cal
The function Delete Cal permits to delete the correction file marked in the Cal List by means of the
selection bar. This keypad can only be operated if there are entries in the Cal List .
Close
The keypad Close closes the Cal Manager and returns to the main menu.
Set Base Cal
The function Set Base Cal is used to determine the base calibration, which is modified by the
commands Embedding and De-Embedding in the main menu. It is possible to choose between active
calibration (button Active Cal) and the calibration marked in the Cal List (button Selected Cal from List).
This selection is to be made before actuating the keypad Set Base Cal.
The currently selected base calibration is indicated both at the top left in the frame Set Base Cal for
(De-)Embedding and in the frame Base Cal at the top left in the window Embedding or De-Embedding.
Info
The command Info calls up the program information for Software Option ZVR-K9.
The OK button closes this window.
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Application Examples
ZVR-K9
Application Examples
Embedding: Testing SMD Components with a Virtual Matching Network
In the application circuit certain components are embedded into a matching network. For example, highimpedance SAW filters to be integrated into a 50-ohm system must be provided with a transformation
circuit. The behavior in the circuit is determined by the composite network consisting of component and
transformer only. Therefore, these components are often specified together with the matching network
and must therefore also be tested in the matching circuit.
The component test with matching network involves the problem that measurement results of various
test fixtures of the same type are comparable only to a limited extent because of the unavoidable
tolerances of the matching network. This implies that a relatively high measurement uncertainty has to
be assumed, which is to be subtracted from the specified values in the component test and thus results
in a poorer yield. Therefore, it would be favorable to use a virtual, tolerance-free matching circuit in the
measurement instead of a real one.
This virtual matching circuit can either be calculated with the aid of a CAD program, or a physically
existing circuit is measured. The second procedure is to be recommended if there are parasitic effects
which are difficult or impossible to account for in a model.
For testing SMD components, a test fixture is required. Necessary matching networks are often
integrated into this test fixture. If one wants to change over to virtual matching networks, a test fixture is
still to be used for electrical matching of the DUT, however, it is usually less complex and does not
contain a physical matching network. In most cases, the matching network itself cannot be measured on
its own.
Nevertheless, a virtual transformation network can be determined as the “difference“ between the test
fixture with matching network and the fixture without matching network (Fig. 6). The series connection of
virtual network TN∆ and test fixture without network TNU will then be electrically equivalent to the test
fixture with network TNA. One imagines the virtual network to be assigned to the outer ports of the test
fixture that are connected to the network analyzer. Thus it can later be considered in the system error
correction data F so that the modified correction data Fmod are obtained. Due to this definition, the virtual
matching network does not necessarily have to feature the same electrical behavior as the real one
which is integrated at any place in the test fixture.
ideal NWA
F1
TN∆1
3
TNU1
1
DUT
TNU2
Fmod1
real NWA
NWA with virtual TN
Fig. 6:
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TN∆2
F2
Fmod2
TNA1
test fixture with
matching network
test fixture without
matching network
TNA2
real NWA
NWA with virtual TN
Virtual transformation network seen as the “difference“ between a test fixture
with and a test fixture without matching network
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ZVR-K9
Application Examples
A typical test fixture has coaxial connectors where the test cables of the network analyzer are
connected, and contacts for the DUT which are matched to the shape of the case of the component to
be measured. For determination of the virtual network the assumption is made that the coaxial
connectors at the test fixtures with and without matching network are identical. The virtual network can
then be calculated by means of three calibrations.
The command Measure Network leads to the window Access to Transformation Network, which permits
to call up the window Indirect Measurement via the keypad Indirect. The reference plane of the outer
calibration started with Outer Cal are the generally coaxial ports of the test fixture to which the network
analyzer is connected.
For the two inner calibrations that are performed at the contacts to the DUT, special calibration
standards are required. By installing these standards into a case corresponding to the DUT, you can
make sure that the field distribution at the test ports is the same for calibration and measurement. Of
course, this is only possible if the case can approximately be regarded as matched and loss-free. In the
case of non-coaxial test ports, the production of precise standards is particularly difficult. It is therefore
recommended to use a self-calibration method such as TRM, TRL or TNA for the inner calibrations,
where not all standards have to be known exactly. For TRM, e.g., it is sufficient to use a piece of a
transmission line with reference impedance Z0 and known length, besides two terminations with Z0. The
REFLECT standard can be implemented by leaving the contacts open in the case of symmetrical test
fixture contacts.
After the calibrations have been performed, the virtual matching network is calculated and stored via the
keypad Calculate Transformation Network. It can then be embedded in the previously recorded
calibration or in a new outer coaxial calibration. If you measure a component in the test fixture without
matching network by means of this modified calibration, the same result will be obtained as if you had
used the original calibration and the test fixture with matching network.
De-Embedding: Measurement of “Embedded“ Components
A further case of application for the Software Option ZVR-K9 is the characterization of embedded
components. These are not accessible for a direct measurement, because they are inseparably
connected with a transformation network. For example, one might want to measure the scattering
parameters of an MMIC, which cannot be removed from its case. Another example is the investigation
of the transmission, reflection and crosstalk of a connector for printed circuit boards. To be able to
connect this connector to a network analyzer, male and female connector are each soldered into an
adapter board with coaxial connections. If the characteristics of the connector alone are to be
determined, the adapter boards must be removed computationally.
If the scattering parameters of the transformation network are known, measurement problems like this
can be solved with the aid of the de-embedding procedure. If it is not possible to simulate the network
with sufficient accuracy using a CAD program, the scattering parameters must be measured. Unlike in
the above application example, the command Measure Network now permits to select direct access to
the network ports. In this case, one calibration must be performed at the inner ports and one at the outer
ports of the transformation network. For non-coaxial devices under test, the calibration procedures TRM
or TNA are suitable. If the transformation network is an SMD case, special standards are required both
for the inner and outer calibration. If reproducible case characteristics can be assumed, it is often useful
for the inner calibration to install the standards permanently in the case.
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Application Examples
ZVR-K9
Measuring a Microstrip Transition
In the de-embedding example mentioned above, one part of the measuring task was to determine the
embedding transformation network. However, it may even be the measuring task itself to determine and
display the S-parameters of a transformation network.
In state-of-the-art microwave circuits, there is a growing tendency towards the exclusive use of planar
transmission line structures without coaxial interfaces. It is conceivable, e.g., that several microwave
modules on ceramic substrates are combined on a printed epoxy motherboard (PCB) which contains
only RF connections and AF circuits to form a single module. The transition from the printed circuit
board to the ceramic substrate must be as low-reflection and low-loss as possible.
If the transition is regarded as a transformation network, it can be determined by forming the difference
between calibrations at the outer ports (on the PCB) and the inner ports (on the ceramic substrate). The
TRM or TNA method should be used for the calibrations. Fig. 7 shows the calibration standards used.
printed circuit board
(TRM-calibration)
calibration substrates
(TNA-calibration)
THROUGH
2x SHORT
NETWORK
2x MATCH
ATTENUATION
contact springs
2x OPEN
contact surfaces
Fig. 7:
Calibration standards for measuring a transition
from printed circuit board to ceramic substrate
The command Measure Network permits to determine the S-parameters of the transition and store them
as a transformation network. To make them visible, the network can be exported in a CAD file format
(e.g. Serenade, Series IV, ADS) and imported by the respective program as a black-box element. Fig. 8
shows the S-parameters of such a transition. Of course, the CAD program also permits to investigate its
behavior in a simulated circuit environment or match a transition model to the measured data by
optimizing the parameters. If required, the modified model can then be imported again as a virtual
network into the Software ZVR-K9.
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ZVR-K9
Fig. 8:
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Application Examples
S-parameters of a transition from PCB to ceramic substrate
25
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ZVR-K9
Index
Index
A
E
Access
Direct.........................................................................15
Indirect ......................................................................14
Access to Transformation Network (Window) ..................15
Active calibration (window) ..............................................17
ADS...................................................................................8
Agilent EESof EDA (CAD programs) .................................8
Ansoft / Compact Software (CAD programs).......................8
Application examples
De-Embedding...........................................................23
Embedding ................................................................22
Measure microstrip transition.....................................24
Application Examples ......................................................22
Auxiliary network .......................................................14, 18
Embedding
Network ...................................................................... 6
Embedding (Command) .................................................. 19
Embedding, Virtual ............................................................ 1
Exit (Command) .............................................................. 14
Export network
Command ................................................................. 10
Window..................................................................... 11
F
File
Import ......................................................................... 9
Output....................................................................... 12
File (Command menu)....................................................... 7
Firmware version............................................................... 3
Formats (files) ................................................................... 8
Functions .......................................................................... 2
B
Base calibration ...............................................................19
Set.............................................................................21
G
C
Getting Started .................................................................. 5
CAD file
Import ..........................................................................5
CAD program.....................................................................2
Cal List ............................................................................20
Cal Manager
Command..................................................................20
Window .....................................................................20
Calibration .........................................................................5
Activate .....................................................................21
Base..........................................................................19
Close .........................................................................21
Inner..........................................................................16
Manage data .............................................................20
Modified.....................................................................19
Outer .........................................................................17
Store ...........................................................................5
TXX ...........................................................................17
Calibration measurement menu .......................................17
Calibration method
Inner calibration.........................................................16
Circuit environment
Simulated ....................................................................2
Command menus ..............................................................7
Connecor Type ................................................................16
H
Hardware Configuration (Window)................................... 13
I
Import
CAD file ...................................................................... 5
Import File
Command ................................................................... 7
Import Network
Window....................................................................... 9
Indirect measurement (window)....................................... 18
Info (Command) .............................................................. 21
Inner calibration (Window)
Define connector and cal method.............................. 16
Installation......................................................................... 4
Introduction ....................................................................... 1
K
key code number............................................................... 4
L
D
LED REM(OTE) ................................................................ 6
Database formats
Input ............................................................................8
De-embedding ...................................................................2
De-Embedding.................................................................20
Device under test
Embed.......................................................................19
Remove network .......................................................20
Direct Inner Calibration
Cal Source (Window).................................................16
TXX (Window) ...........................................................17
Direct measurement (Window).........................................15
Direct Outer Calibration
Cal Source (Window).................................................17
M
Measure Network ............................................................ 14
Measure network (window) ............................................. 17
Measuring task
De-embedding ............................................................ 2
Embedding.................................................................. 1
Unterminating.............................................................. 2
Measuring Tasks............................................................... 1
N
Network
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Index
ZVR-K9
Embedding ..................................................................6
Network export
options.......................................................................11
Network Manager (Window) ............................................12
Status display.................................................................... 6
Super Compact ................................................................. 8
System error correction data
Manage..................................................................... 20
Modify ....................................................................... 20
System Requirements ....................................................... 3
P
T
Point grid ...........................................................................8
Port..................................................................................16
Preparation ........................................................................5
Program Information ........................................................21
Test port.......................................................................... 16
Touchstone ....................................................................... 8
Transformation network
Access ...................................................................... 15
Direct measurement.................................................. 15
Embedding................................................................ 19
Indirect measurement ............................................... 18
Inverse........................................................................ 2
Measure.................................................................... 14
Store ......................................................................... 17
Virtual ......................................................................... 1
Transformation network..................................................... 1
Transformation Network
Management ............................................................. 12
R
Reference Part ..................................................................7
REMOTE status.................................................................7
S
Save Export File (Window) ..............................................12
Save transformation network
Window .....................................................................10
Save transformation network (window) ............................17
Select Export File Options
Window .....................................................................11
Serenade ...........................................................................8
Series IV............................................................................8
Setup program...................................................................4
Simulated circuit environment ............................................2
SMD Components ...........................................................22
S-parameters
Import ..........................................................................7
Output .......................................................................10
Start calibration................................................................15
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V
Version number (Firmware)............................................... 3
Z
ZVR-K9
Functions .................................................................... 2
LED display................................................................. 6
I.2
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