AKELA Vector Network Analyzer (VNA) Quick Start Guide

Transcription

1 AKELA Vector Network Analyzer (VNA) Quick Start Guide

2 Copyright AKELA, Inc. 2012, all rights reserved LabVIEW and LabWindows are registered trademarks of National Instruments Incorporated Excel is a registered trademark of Microsoft Incorporated MATLAB is a registered trademark MATHWORKS Incorporated

3 CONTENTS AKELA VNA Evaluation Kit Contents 4 Front Panel 5 Connecting the VNA 5 Unit Status Lamps 6 Connecting to a PC or Network 6 Installing the AKELA VNA Application 8 Updating the AKELA VNA Application 8 Starting the AKELA VNA Application 8 VNA Display and Control 10 Stimulus Control Panel 13 Calibration Control Panel 14 Display Control Panel 15 Marker Control Panel 16 Data Control Panel 18 State Control Panel 19 Special Control Panel 20 Making Measurements 21 Appendix A 23 3

4 AKELA VNA Evaluation Kit Contents The evaluation kit contains all the equipment required to evaluate the AKELA VNA. Software Installation CD Vector Network Analyzer Assembly, AKELA Vector Stimulus Unit (AVMU) and S-Parameter Test Set 12VDC Power Adapter and Power Cord Network Cable, Cat 5E Crossover (null modem) 2 Type N Male to SMA Female Adapters 2 SMA Male to SMA Male Coaxial Cables, 12 inch Economy SMA calibration kit, 50Ω Load, Short, and Open 915 MHz Band Pass Filter 4

5 Port 1 Status Lamp AKELA VNA Front Panel S-Parameter Test Set Port 2 Status Lamp Stimulus Measurement Unit (AVMU) Port 1 and Port 2 Status Lamps indicate which S-Parameter Test Set port is active. Connecting the VNA Connect the 12VDC Power Adapter cables to the AC Mains and the 12VDC connector on the Stimulus Measurement Unit. Use the supplied Cat 5E network cable to connect the Stimulus Measurement Unit to the Ethernet port on your PC or system network. To turn the VNA On or Off, press and hold the power button for 2 seconds. 5

6 The VNA Status Lamps PWR: On when power is applied SCAN: On when measurements are being acquired LAN: On when connected to a network/pc NETW ACTY: Flashes when network activity is detected BATTERY: Indicates state of charge when using external battery power FAULT: Indicates an internal fault has occurred, e.g. over temperature, over current, under voltage, etc. Connecting To A PC Or Network Communication with the AKELA VNA is through the 100 Base-T Ethernet connection and may be accomplished either by direct connection to a computer or over a LAN. The Ethernet cable supplied in the evaluation kit is a Cat 5E crossover cable and may be used for connecting the VNA to a computer or LAN. Since the VNA does not automatically sense TX/RX polarity, a crossover cable must be used if the computer or LAN connected to the VNA does not automatically sense polarity. Each VNA is assigned an Ethernet Address in the range of to as the factory setting. This address is fixed. The VNA shipped in the evaluation kit is set to IP The VNA does not implement the DHCP protocol and does not support Internet Control Message Protocol functions such as PING. 6

7 If the VNA is connected to a LAN through a switch or router, the VNA should be able to communicate without any changes to your computer network settings. If the VNA is connected to a computer directly, the user will need to change the computer's IP address setting to a fixed IP address that is in the same range as the VNA s. To set the IP address of your computer, go to the properties tab of the network interface on your computer, select Advanced, select Internet Protocol, Properties, click on use the following IP address and set the fixed IP address. When setting the computer to a fixed IP address, it must be in the range of to excluding the address of the VNA ( ). Set the subnet mask to After the IP address of your computer has been set, the VNA application should be able to communicate with the VNA normally. On some computers, the user may need to disable any other network connections (e.g. wireless connection) that are not connected to the VNA. AKELA VNA Application Program Installation The software package distributed with the AKELA Vector Network Analyzer provides a LabVIEW-based application that executes under the LabVIEW 8.6 Run-Time Engine. The software will install the National Instruments LabVIEW 8.6 Run-Time Engine and the AKELA VNA application to your computer. It is not possible to modify the AKELA VNA application, access the AKELA VNA drivers, or create new LabView applications using the installed software. The user must obtain a separate license from National Instruments to modify the AKELA VNA application or create their own LabView applications for the AKELA VNA. 7

8 Application Installation Insert the software installation CD into your CD drive. Navigate to the CD drive. In the root folder of the CD Drive, double click on the file Setup. exe. The Destination directory window will display. To install software in a different location, click the browse button and select another directory. Click Next when done. The Start Installation Dialog will appear. Click next to begin installation. When installation of the software is complete, click the Finish button. Updating the AKELA VNA Application Should you need to update the VNA application after initial installation of National Instruments LabWindows/CVI Run-Time Engine, an application update archive will be provided. You will be replacing the AKELA VNA Application and the initialization files in the installation folder. Close the AKELA VNA application if it is running. Save the update archive file, typically named AKELA VNA Update V1_xx.zip, to a location on your computer. Use the Windows Zip file Extraction Wizard to extract the files from the archive. Copy the extracted files, including the data folder, to the AKELA VNA installation folder, usually C:\Program Files\AKELA VNA, overwriting the existing files. There is no need to restart the computer after an update is installed. Starting the AKELA VNA Application For Microsoft Windows Vista or Windows 7 installations, the user will need to allow the AKELA VNA application to Run as an administrator. From the start menu, right click on the AKELA VNA 8

9 start menu item, select Properties, select the Compatibility tab and check the Run this program as an administrator box, then click OK. To start the AKELA VNA application, go to the start menu and click on the AKELA VNA program item. The VNA application will start and display an informational notice, Searching for AVMU units. If the VNA application fails to find any AVMU units attached to the network, it will display the informational message, No AVMU units found. Click OK to continue. If the user has no AVMU (VNA) attached to the network, the AKELA VNA application will begin to run using simulated data, thereby allowing the user to explore the features and controls of the AKELA VNA application. If the user has an AKELA VNA connected to the network but the VNA application fails to detect the VNA, some common reasons for this may be: - The VNA is connected directly to the Ethernet Port on the computer and a static IP address has not been set. - The VNA is connected directly to the Ethernet Port on the computer and a crossover Ethernet cable is required. - There is an IP address conflict on the network. For example, a DHCP server may have assigned the VNA IP address to another 9

10 computer or device. If the user's network has static IP addresses assigned, identify the device and assign it a new, non-conflicting IP address, and exclude the VNA IP address from the DHCP server's automatic assignment list. AKELA VNA Display and Controls The left side of the VNA application display area is dedicated to data display. One, two, or four measurement display panes may be selected. The right side of the VNA application display area is dedicated to the control panels, where the user may access the controls available in the application. 10

11 To access the different control panels within the VNA application, click on the tabs on the right edge of the display area. Most of the controls and features will be familiar to anyone experienced with the use of RF Network Analyzers in general. The location and function of many of the on screen display controls are illustrated and described in the next section. VNA Display Data Area The VNA application is capable of displaying all four of the measured S-Parameters at the same time. The active RF paths are selected in the Stimulus Control Panel. Axis Scale minimum and maximum values for each display pane may be changed by double clicking on the Axis Scale End Point values on the display pane and entering the desired values. The 11

12 display's X and Y Axes may also be set by clicking on the X and Y auto scale buttons. The display panel Zoom, Pan, Marker, and Scale controls are shown below. Zoom tool Marker tool X-Axis autoscale S parameter selection Pan tool Y-Axis autoscale X-Axis scale controls Y-Axis scale controls The S-Parameter pull down menu allows selection of which S- Parameter will be shown in the display pane. Click on the Pan tool to enable panning the data in the X and Y Axis. Click on the Zoom tool to display and select the zoom options. Click on the Marker Tool to enable moving the markers within the display pane. In the Zoom and Marker Tool control group the selected option will persist within that display pane until another function is selected. Click the X and Y Axis Auto-scale buttons to auto-scale the X or Y Axis within the display pane. Click the X and Y Axis scale control buttons to display, select and set additional Axis scale control functions. The data format and scaling for each display pane may be set independently. The available display formats are: Real, Imaginary, Log Magnitude, Phase, Delay, Polar, Smith Chart, FFT (magnitude) and Data format selection Marker X axis value 12 Marker Y axis value

13 FFT (phase). Click on the Data Format Selection box and select the desired format for that display pane's data. The Marker Value Displays show the X and Y axis values for each of the data markers. Click on the desired marker box to turn the marker on and off. Stimulus Control Panel This panel allows you to control all of the stimulus parameters of the VNA and to select which S-Parameter paths to measure. S-Parameters to measure are selected with the radio buttons in the Active RF Paths selection box. Start and stop frequencies for the sweep are entered in the F min and F max text boxes. Each text box will support frequency values with up to 3 decimal places over a range from 250 to 2048 MHz. The arrows next to the text boxes will change the frequency in steps of 1 MHz. There are 12 selectable frequency hopping rates varying from 0.04 to 45 khz that are selected by clicking in the text box, or by using the arrows next to the text box. The number of points per frequency sweep is entered directly in the text box with valid values being from 2 to 4096 points. The nominal receiver gain setting for VNA operation is 6 db. Except under special conditions the valid gain values are 0, 3 and 6 db, since higher values will exceed the dynamic range of the measurement receiver. Attenuation in the transmit path can be set to values between 0 and 31 db in steps of 1 db. The setting selected is applied to both Ports 1 and 2. If the user s Device Under Test 13

14 (DUT) has gain, the receiver gain must be reduced, or the attenuation value increased by an amount equal to the DUT gain to maintain measurement accuracy. All of the other boxes in this panel are informational. Single path time is the time it takes to make a single S-Parameter measurement. Unambiguous delay is the maximum delay, or FFT time, that can be accurately displayed with the current bandwidth and number of points selected. The status box shows the current state of VNA data acquisition. To stop the data acquisition process, click on the Quit button. To restart, click the run arrow in the upper left corner of the main display. Calibration Control Panel AKELA s VNA comes with a factory calibration file so the VNA may be used immediately for making measurements as long as there are no special test fixtures involved in your test measurement setup. Each VNA is calibrated at the factory before shipment using the maximum VNA resolution with precision calibration standards. A factory calibration file is shipped with each VNA and is stored in the data folder within the VNA application installation folder with a name of the form Factory004.tdms where the last three numbers in the file name are the serial number of the VNA. The calibration file is automatically loaded at startup. During normal operation The calibration file will be interpolated by the calibration routine if the user s setting are different from those used at the factory to allow for different stimulus settings without completely invalidating the calibration. For the best ac- 14

15 curacy corrected data, however, a calibration should be performed for your particular stimulus settings. Both 1-Port and 2-Port calibrations are supported in the calibration control panel with the procedure for each being similar. For a 1-Port calibration, select the port for which the calibration is desired and then click on the buttons one at a time to be guided through the calibration using an Open, Short, and Load. The 2-Port calibration requires more steps because it calibrates both ports and includes a Through measurement. In Simulate mode, the Calibration functions are not available. After calibration, the calibration may be saved as a file for later use by pressing the Save cal file button and providing a suitable name for the file. The file may be recalled for use at a later time by using the Load cal file button. You may also specify which calibration to use by clicking in the Calibration to use text box and selecting 1-Port, 2-Port, or None. If None is selected, the uncorrected data will be displayed but the current calibration data will not be cleared from memory. At any time during VNA operation, you may determine the stimulus conditions under which the current calibration in use was performed. This is displayed in the Native Range box. For best results this should match the current VNA stimulus settings. If the calibration being used is from a previous calibration file that has been loaded, the name of the file will be displayed in the text box below the Clear button. The Clear button clears the current calibration data from memory. When the calibration data is cleared from memory the VNA displays raw uncorrected data. Display Control Panel This control panel allows you to control the number of VNA display panes and to select the number of VNA sweeps to aver- 15

16 age for smoothing the displayed data. One, two, or four display panes can be selected by using the associated radio buttons. Each display pane is identified by a letter A through D. These letters are used by the VNA application when using Markers and performing Marker Math and show up in the lower left corner of each display pane. The radio button for the selected option is highlighted. To choose the number of sweeps to average, enter the value into the text box and then press the Reset button. The status bar underneath the text box will turn red until the desired number of sweeps has been reached. The maximum value allowed is 512. Marker Control Panel Up to five markers are available for each display pane. The the scroll bar to the side of the Marker selection area will allow you to navigate to the selection boxes for display panes B through C to select additional markers. Markers are enabled or disabled by clicking on the marker buttons, A1, A2... B1, B2..., etc. for each display pane. When selected, a marker is highlighted in color. Markers can be of two types, Data or Free. Data makers are tied to a data point on a display pane trace, while 16

17 Free markers may be placed anywhere within a display pane. This is useful for setting targets or limits on screen. Select the type of marker by using the arrows next to the Type text box associated with the marker. The value for the marker is entered in the Position text box associated with each marker. Marker values will only be shown to one decimal place. Markers are normally independent among the selected display panes. However, they may be linked between panes by using the Marker Links area of the control panel. First select a link by clicking on a radio button. Clicking on the first marker selection box will produce a fly out menu that will allow you to check which marker to begin the link. Clicking on the second selection box will similarly allow you to select the marker number that finishes the link. To unlink the marker simply click the radio button again. When linked, markers track between the selected display panes. To access additional marker pairs to link, use the scroll bar to the side of the Marker Links selection area. 17

18 AKELA s VNA application will automatically do calculations using data values associated with markers. Clicking on a Marker Math radio button will enable or disable this capability. Marker math is enabled when the radio button is highlighted. As with selecting marker links, clicking on a marker selection box will produce a fly out menu that allows you to select which marker to use for calculation. The mathematical operation performed on the marker data values is selected by clicking on the mathematical symbol between the two marker selection boxes. Choose from one of the four available functions, +, -, * and /. The result of the math operation is displayed in the text box. Data Control Panel The Data Control Panel provides a variety of methods for you to save data for later analysis, test reporting, or performance archiving. You may export the current data from all open display panes directly to a Microsoft Excel spreadsheet for custom processing. With Excel open, click on the Export to Excel button. In this option, a separate file is not saved so it will be necessary to save the Excel spreadsheet if you want a permanent file record. Alternatively, you may export the data directly to a file in a comma separated variable format (CSV). Clicking the Export to CSV button saves the current data from all open display panes to a CSV file that may be read later with Excel or other applications such as MATLAB. 18

19 The Export to S1P (1) and (2) buttons allow you to save current data to a 1-Port S-Parameter file for Ports 1 and 2 respectively. The Export to S2P (1) button saves the current data to a full 2-Port S-Parameter file for Ports 1 and 2. To save a single frame of data for the current data acquisition or to load a previously saved single frame of data, use the Save snapshot and Load Snapshot buttons respectively. A loaded snapshot file will allow you to view and manipulate the saved data in the VNA application. Similarly, the Save stream and Load stream buttons allow you to save and reload a time history of data to view and manipulate in the VNA application. State Control Panel When the quit button is pressed or the VNA is turned off, the current operating setup state is saved and reloaded upon system startup. While this is convenient, it is often useful to be able to recall a previous operating state to minimize setup time after changing to a different type of measurement. This panel allows you to both save special setup states of the VNA, and to reload them at a later time. The state includes all of the stimulus, calibration, display, marker, and special values that you have selected to define the current operation of the VNA. Use the Save state and Load state buttons to perform these operations. The Startup tab allows you to specify which Control panel to show beside the Data Display Area on system startup. Clicking on the Startup tab will produce a fly out menu from which you can select the desired control panel. In order to save or load a state, the VNA application must be running. 19

20 Special Control Panel This control panel provides a set of advanced functions. The Memory functions allow you to store a snapshot of the current data traces to the application memory. Click on the Capture button to store the traces to memory. Once the traces are stored, you will be able to change a DUT and use the Operation text box to select a mathematical operation for comparing the traces in memory with the current data traces. Click on Clear to clear the current data from memory. A reference plane extension is normally used to adjust the reference plane of the measurements to compensate for removal of the calibration standards, or to adjust for test fixture reference plane offsets. The Reference plane extension area of this control panel allows you to make this adjustment electronically. Use the slider or the up down controls to adjust the reference planes of the test ports. You may also input a value directly into the text box. The Unwrap Phase button will automatically perform a best straight line fit of the unwrapped phase of the current data in the target window. This is useful for rapidly adjusting for large phase offsets in a test configuration, for example removing the phase and time delay of long test cables. The Plot Options text boxes allow you to select the units (dbm, dbv, Degrees, Radians) for the display pane data plots and to set the reference for the Smith chart and the number of FFT points. 20

21 Making Measurements The AKELA VNA operates in much the same way as any other Vector Network Analyzer. However, there are a few differences that are noteworthy. VNA control functions that have been changed in the control panels only take effect if the VNA application is running and acquiring data. If the VNA application has been stopped using the Quit button, the application will need to be restarted using the start arrow on the upper left of the main display area in order for any operating parameter changes to take effect. The AKELA VNA takes a complete set of S-Parameters with every measurement cycle, acquiring S11, S21, S12, and S22 as well as a set of reference measurements used by the internal calibration routines. If the user's Device Under Test (DUT) exhibits gain, the VNA Gain must be reduced or the VNA attenuation setting must be increased (reduced output stimulus power). These controls are found on the Stimulus control panel. The output power or receive gain must be adjusted by an amount equivalent to at least the gain of the DUT. Example measurement Connect the 915 MHz Band Pass Filter supplied with the evaluation kit between Test Port 1 and Test Port 2. Start the VNA application. From the State control panel, click on Load State, browse to the installation folder where the VNA application was installed, then open the data folder and click on the state file: S12_765M_1065M_915M_BPF_30K_401Points_4panes_FFT. tdms Click on OK and the VNA display should appear as shown on the next page. 21

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23 Appendix A External communication with the AKELA VNA application The AKELA VNA software can be integrated into your workflow in several ways: 1) ActiveX (Microsoft Automation) support enables the AKELA VNA software to export its measurement results to another software package at runtime, such as Excel, Igor Pro, Origin, and others. 2) For customers with existing LabVIEW work flows, AKELA can deliver subvis tailored to your needs - whether that be a platform on which to build your own new features, or simply a measurement subvi. 3) As a Windows DLL, the AKELA VNA software can be accessed by any in-house software. Contact AKELA for more information on how to integrate AKELA VNA software with your workflow. 23

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