Using ECal

This topic discusses all aspects of performing an ECal:

See Also:

ECal User-Characterization

Perform a 4-Port Cal with ONE 2-Port ECal Module

Restore ECal Module Memory

See other Calibration Topics

ECal Overview

ECal is a complete solid-state calibration solution. Every ECal module contains electronic standards that are automatically switched into position during a measurement calibration. These electronic standards have been measured at the factory and the data stored within the memory of the ECal module. The analyzer uses this stored data, along with the measured data, to calculate the error terms for a measurement calibration.

ECal modules are available in 2-port and 4-port models and a variety of connector types, covering many frequency ranges. See Analyzer Accessories for more about available ECal modules and ordering information.

You can perform the following calibrations with ECal:

Verify the validity of a mechanical or ECal calibration with ECal confidence check.

Care and Handling of ECal Modules

You can improve accuracy, repeatability, and avoid costly repair of equipment in the following ways.

Power Level into an ECal module


Compression level

Damage level

N469x series

-5 dBm

+10 dBm

N4432A series

N4433A series

-7 dBm

+20 dBm

N4431x series

+7 dBm

+20 dBm

N755xA series

-5 dBm

+10 dBm

8509x series

+9 dBm

+20 dBm

The power level can be increased after calibration with minimal impact on measurement accuracy.

Connect ECal Module to the Analyzer

ECal modules are controlled and powered through a USB connection. When you connect the module, the type of module, frequency range, and connector type are automatically recognized.


Important Note: DO NOT connect/disconnect USB devices during ECal calibrations. Doing so may cause problems with the calibration.


See Important First-time USB connection note.

ECal modules connect to the USB port on the front or rear panel of the PNA.

  1. Wear a grounded wrist strap when making connections.

  2. Connect the USB cable Type B connector to the ECal module and the USB cable Type A connector to the front or rear panel USB connector of the analyzer, as shown in the following graphics.

    ECal Module USB Port                                                               Analyzer Front Panel USB Port



How to Perform a Calibration Using ECal

Select an ECal module that has connectors of the same type and gender as the DUT. If such an ECal module is not available, a module with connectors different from the DUT can be used by using Advanced Settings or User Characterization. See Also: Perform a 4-Port Cal with ONE 2-Port ECal Module

Connect the ECal module ports to the analyzer ports. During the calibration process the analyzer can either automatically detect how the ECal module is connected, or the orientation can be performed manually.

  1. Connect the ECal module USB cable to the analyzer USB. See Connect ECal Module to USB.

  2. Allow the module to warm up until it indicates READY.

  3. Enter the analyzer settings. See Set Up Measurements.

  4. Do one of the following to start the Calibration Wizard

Using front-panel
[softkey] buttons

Using Menus

  1. Press cal

  2. then [Start Cal]

  3. then [Cal Wizard]

  1. Click Response

  2. then Cal

  3. then Cal Wizard

  1. In the Calibration Wizard Begin dialog box, click Use Electronic Cal (ECal).  

Note: To calibrate with more than one ECal module, select SmartCal, then choose the ECal modules as your Cal Kits.


Select Calibration Ports and ECal Module dialog box help

Allows you to select calibration type and settings.

Cal Type Selection / Configuration  Select the number of ports to calibrate.  Then select the port number configuration.

4 Port ECal

3 Port ECal

2 Port ECal  

1 Port ECal- (Reflection)  Advanced Settings are not available.

View/Select ECal Module  Click to Select the ECal module if more than one ECal module is connected to the USB. Also, Select the User Characterization within the module. Learn more about User Characterization.

Show Advanced Settings  Check to display the Advanced Settings when Next is clicked.

Back  Return to Cal Wizard Begin dialog. If checked, you can clear the Save Preferences checkbox to see the Begin page when the Cal Wizard begins.

Note:  ECal isolation is not performed. The inherent isolation of the analyzer is better than that attained with correction using an ECal module.

Terminate any unused ECal ports with a 50 ohm load. Refer to Determining Effects of Not Terminating Unused ECal Ports.


ECal module not found dialog box help

When this dialog appears, the ECal module is not connected or has not been recognized by the network analyzer.

Retry  Check the USB connections and click to continue.


  • If your ECal module is not detected, try to unplug, then reconnect to the USB.

  • When the ECal module is connected to the network analyzer for the first time, it may take approximately 30 seconds for the analyzer to recognize the module and make it available for calibration.

  • For best accuracy, allow the ECal module to warm-up until it indicates READY.

  • Keysight 8509x and N4431 ECal modules, when first connected, draw significantly more current than other modules. This could cause the USB to stop working in certain situations. See USB limitations.

  • See Connect ECal Module to USB.


Select Module and Characterization dialog box help

Note: User Characterizations listed in the dialog below that have no temperature shown cannot be temperature-compensated during calibrations. Also, this is true of CalPod as ECal characterizations that were performed prior to this temperature capability in the VNA firmware, because temperature was not measured-and-recorded. However, the firmware will still recognize those and allow them to be used for cals.

ECal Module  Select one of the ECal modules that are connected to the analyzer.

Detect Connected ECals  Click to rescan the USB for ECal modules.

Available Characterizations  

ECal Module Memory - Displays the factory and user characterizations that are stored in the ECal module.

Instrument Disk Memory - Displays the user characterizations that are stored in Disk Memory. Learn more User Characterizations in Disk Memory.

Temperature - Displays the temperature reading at the time a characterization was performed.

The following is an example of a Calset Properties dialog for a cal performed using characterized CalPod as ECal. The information in the dialog confirms which of those characterizations were temperature-compensated during calibration. The (compensated) notation for CalPod serial # 10001234 indicates that the CalPod’s characterization was temperature-compensated when that cal’s error terms were computed (it also implies the factory thermal data for that CalPod must be present on the VNA). Whereas the (uncompensated) notation indicates that temperature-compensation could not be done for that characterization during the cal, which could mean either that one is an older characterization that didn’t record its temperature, or else factory thermal data for that CalPod serial # was not installed on the VNA.


Select the characterization data to use for the calibration. Once selected, that characterization becomes the default selection until the analyzer is turned OFF and restarted. When restarted, Factory again becomes the default selection.


Error: Frequency Range dialog box help

When this dialog appears, the current cal standards (or ECAL module) does not cover the current frequency range of the measurement. Do one of the following to correct the problem:

Cal Kit Class Category  Not available with ECal modules.

Frequency  Change the frequency range of the active channel.

Edit  Not available with ECal modules.

Back  Select a different characterization that covers the required frequency range.

Cancel  Re-characterize the module with an increased frequency range.


Select DUT Connectors and Cal Kits dialog box help

If the ECal module or selected User Characterization has more than one connector type, then the following dialog box is presented which allows you to describe the DUT connector type. Otherwise, click next to proceed to Advanced Settings (if checked) or ECal Steps.


The available connectors are listed for each DUT port.


Advanced Settings dialog box help

Thru #n

Lists the proposed Thru connections to be made during the calibration process. You can change these Thru connections to better suit your test setup.

Add Thru

Click to add a Thru connection. Learn more

Remove Thru

Select a Thru by clicking the "Thru #N" field or the "1st Port / 2nd Port" field. Then click "Remove Thru". This selection is NOT available if the selected Thru is required for the calibration.

1st Port / 2nd Port

Click to change the two ports to be included in the Thru connection. The order of the port numbers (1st or 2nd) is not critical.

Thru Cal Method

Lists the available Thru Cal methods for the specified port pairs.

Learn about ECal Thru Methods

Cal Type/ Stds

Click to invoke the View / Modify Properties of Cal dialog box

Do orientation

When this box is checked (the default setting) the PNA automatically senses the model and direction in which an ECal module port is connected to the PNA ports. If power to the ECal module is too low, it will appear as if there is no ECal module connected. If you use low power and are having this problem, clear this check box to provide the orientation manually.

Orientation occurs first at the middle of the frequency range that you are calibrating. If a signal is not detected, it tries again at the lowest frequency in the range.

Choose delta match

Available only when a Delta Match Cal is required.



Specify how the ECal module is connected dialog box help

This dialog box appears when the Do orientation checkbox in the previous dialog box is cleared.

Click the ECal Port that is connected to each PNA port.



Electronic Calibration Steps dialog box help

Note: Beginning in PNA Rev. 6.0, ECal can be performed with External triggers. Learn more.

Displays the instructions for each measurement required for calibration.

Measure  Measures the ECal standards.

Done  Click when last standard has been measured.

Saving an ECal Calibration

When complete, you can save the new calibration. Learn how.