VectorStar™ MS4640A Series Microwave Vector Network Analyzers : AutoCal Procedures : AutoCal - Two Port Cal - True Through
 
AutoCal - Two Port Cal - True Through
This procedure performs an AutoCal procedure using a full two port calibration where a True Through (or external through) is required.
Required Equipment
• VectorStar MS4645A or MS4647A VNAs with V (m) test port connectors, with Option 070 70 kHz Low Frequency Extension.
• 36585V-2MF Precision AutoCal Module, with V (f) and V (m) connectors and required power and control cables. The AutoCal Characterization file has been loaded onto the VectorStar.
• Test port cable with V (f) to V (m) connectors
• Test port cable with V (f) to V (f) connectors, or a V (f)-V (f) adapter.
Procedure
1. Power up the VectorStar.
2. Set the required Frequency Start, Frequency Stop, and Number of Points parameters.
• Pre-Calibration Instrument Setup.
3. If required, set up other parameters as required such as Segmented Sweep, IFBW, Averaging, and Power and Attenuation.
4. Make the necessary cable connections between the AutoCal Module and the VectorStar:
a. Connect the Test Cable V (f) - V (m) between Test Port 2 V (m) and the AutoCal V (f) port.
b. Connect the Test Cable V (f) - V (f) between Test Port 1 V (m) and the AutoCal V (f) port.
c. Connect the Serial Control Cable between the DB-9 connector on the AutoCal Module and the Serial (10101) Port on the VectorStar back panel.
d. Connect the coaxial power plug on the Power Supply Module to the AutoCal Module and the other end to AC power.
5. Once connected to power, the Power LED illuminates as green. When the AutoCal module has warmed up, the LED illuminates as blue.
Precision AutoCal 36585V-2MF Cable Connections for True Through
1. VectorStar MS4645A or MS4647A VNA with V Test Port Connectors
2. 36585V-2F Precision AutoCal Module
3. AutoCal Power Supply Module connected to AC Power
4. AutoCal DB9 (m-m) Signal Cable connected to VNA Rear Panel Serial 10101 Port
5. V (f-f) Adapter connected to VNA Test Port 1
6. V (m-f) Test Cable connected to VNA Test Port
Schematically, the connections shown in Figure: Precision AutoCal 36585V-2MF Cable Connections for True Through above are shown in Figure: AutoCal True-Through Connections.
AutoCal True-Through Connections 
Part 1 – AutoCal True Thru Procedure
1. VNA Test Port 1 V (m)
2. V(f-f) Test Cable
3. 36585V-2MF AutoCal Module
4. V (m-f) Test Cable
5. VNA Test Port 2 V (m)
6. Resultant reference planes during first AutoCal procedure.
Part 2 – AutoCal True Thru Procedure
7. After initial calibrations, user is directed to remove AutoCal module and connect test cables. At all times during the calibration procedure, the AutoCal module must be connected to the VNA and to AC power.
8. Connect the two Test Cables together to complete the through calibration.
6. Navigate to the AUTOCAL SETUP menu:
• MAIN | Calibration | CALIBRATION | Calibrate | CALIBRATE | AutoCal | AUTOCAL PORTS | 2-Port Cal | AUTOCAL SETUP
7. On the AUTOCAL SETUP menu, if the Cal Type, Thru Type, and Module Orientation display buttons do not show the correct values, select the Modify Cal Setup button.
a. The MODIFY 2-PORT AUTOCAL SETUP dialog box appears.
b. Change the settings as required.
c. In the Cal Type Select area: Select the Full Two Port radio button.
d. In the Thru Select area, select the True Thru radio button and the THRU INFO dialog box appears.
e. Enter information about the through line. Enter 0 length and 0 dB/mm loss (and a reference frequency of 0, which forces it to use that loss at all frequencies) and 50 ohm impedance. Select OK to close the dialog box.
• Select the Auto Sense Module Orientation check box which allows the AutoCal module determine the left/right cable identification.
• Click OK to close the dialog box.
Note 
All existing system setups such as IF Bandwidth, Averaging, and Power Level will be applied during the calibration procedure.
8. When ready, click the Begin Cal button.
9. If the AutoCal module is connected incorrectly, the AUTOCAL MODULE NOT DETECTED warning message appears.
• Correct connections as required and click Retry.
10. A status dialog box with a progress bar appears after an AutoCal sequence has started. The status messages define has far the program has progressed and if any user actions are required.
11. At any time, the AutoCal sequence can be cancelled by clicking the dialog box Abort button.
12. A dialog box will appear when the true through is to be connected.
13. Connect the Test Port 1 test cable to the Test Port 2 test cable.
AutoCal True-Through Connections - Module Removed 
1. MS4645A or MS4647A VNA with V Test Port Connectors
2. 36585V-2MF AutoCal Module
3. AutoCal Module Power Supply connected to AC Power. AutoCal module and connect test cables. At all times during the calibration procedure, the AutoCal module must be connected to the VNA and to AC power.
4. AutoCal DB9 (m-m) Signal Cable connected to VNA Rear Panel Serial 10101 Port
5. V (f) to V (f) Adapter connected to Test Port 1 V (m)
6. V (m-f) Test Cable connected to V (f-f) adapter and Test Port 2 V (m)
14. After connecting the through, select Continue.
15. When the auto calibration is complete, a status message appears with a statement about assurance passing or failing. On the CALIBRATION menu, the Cal Status field button shows ON.
16. Closing the dialog box returns to the CALIBRATION menu.