CalPod (Opt 301 or 302)

CalPod is a system that simplifies the process of recalibrating the PNA without requiring the removal of the DUT or the physical connection of standards. This allows recalibration from a remote location such as when the DUT is in a temperature chamber.

In this topic:

Other Calibration topics

Process Overview

Note: The following overview assumes the CalPod system has been installed and configured.  See the CalPod User's Guide for installation instructions at:

The following process assumes a 2-port DUT connected to the PNA ports 1 and 2 through CalPod modules as follows:

The  Blue  boxes represent CalPod modules with internal Thru, Short, Open, and Load states.

  1. After configuring and assigning CalPod modules to PNA ports 1 and 2, connect the CalPod modules to the PNA, directly or using short cables. Learn how to configure CalPod.

  2. Setup measurements on a channel.  An IFBW of 1 kHz or lower with eight averages is recommended.  CalPod does not support measurements below 100 MHz.

  3. Perform a full 2-port calibration for the channel with the CalPod outputs as the reference plane.

  4. Click Initialize Channel to automatically perform the following steps:

    1. The OPEN, SHORT, AND LOAD states of both Calpod modules are switched in and S11/S22 are measured.

    2. The resulting measurements are stored in the channel's Cal Set as additional standard measurements. These measurements are used to characterize the Calpod states - they are NOT used at this time to change the error correction.


  • Because the OPEN, SHORT, AND LOAD states in the CalPods are measured, it is not important what is connected to the CalPod when Initialize is pressed. Therefore, for highest accuracy, click Initialize IMMEDIATELY and ONLY ONCE after performing the calibration - before causing ANY cable movement.

  • If an adapter is required to connect the DUT to a CalPod, use a high-quality adapter. Any temperature drift due to the adapter is NOT recorrected.

  • Always connect the DUT as close as possible to the CalPod modules.

  1. Connect the DUT to the CalPod outputs.

  2. Click Recorrect Channel or Recorrect All Channels whenever necessary.  Any of the following actions will cause the current calibration to become invalid and require recorrection:

    1. Moving the CalPod modules to the ends of long cables.

    2. Changing the cables.

    3. Extreme temperature variations.

    4. Measurement drift over long time periods.

  3. The following steps occur automatically during recorrection for the active channel:

    1. The OPEN, SHORT, AND LOAD states of both CalPod modules are switched in and S11/S22 are measured.

    2. Additional (de-embedded) error terms are computed to compensate for changed conditions from the Initialize measurements.

    3. Another Cal Set is created using the original name with the CalPod number appended. The modified error terms are saved to that Cal Set and applied to the channel. The measurements are now fully corrected.

How to start the CalPod dialog

Using front-panel
[softkey] buttons

Using a mouse with PNA Menus

  1. Press cal

  2. then [More]

  3. then [CalPod]

  4. then [CalPod...]

  1. Click Response

  2. then Cal

  3. then CalPod

  4. then CalPod

CalPod dialog box help

Learn all about the CalPod process.(Scroll up)

Initialize Channel  Calibrated measurements of the CalPod states are performed as initial reference data points for the active channel.

Initialize All Channels  Calibrated measurements of the CalPod states are performed as initial reference data points for all current channels.  This command is not recommended, it is generally preferable to initialize each channel immediately following calibration.

Recorrect Channel  Recorrects the active channel Cal Set to match the initial reference.

Recorrect All Channels  Recorrects the Cal Sets on ALL channels that were initialized.

Correct Power  This checkbox causes power to be recorrected ONLY when source power correction data is stored as error terms in the CalSet. This occurs only when a Guided Power Cal is performed (on the standard channel) OR when an app channel is calibrated such as a FCA, GCA, IMD, and Noise Figure channel. This checkbox has NO effect when a S-parameter (only) Cal or a standard Source Power Cal has been performed, because source power correction data is not stored in the CalSet. To see if the source power cal can be modified, examine the Calset for "SourcePowerCorrection(n)" terms where "n" is the port number.

When any of the above power cals have been performed, and when this box is checked, the power output at the VNA port is adjusted to compensate for any change in path loss when Recorrect is performed.  For example, if the path loss between the VNA port and the CalPod was increased by two dB following initialization, then the VNA output power will be increased by two dB upon recorrection.  Do this when you add a significant amount of loss in the calibration path, or when the power level at the DUT is important.

When a significant amount of loss is introduced in the calibration path, it may not be possible to increase the source power enough to overcome the loss. In this case, an Unleveled source message may appear on the PNA screen.

When the checkbox is cleared, the source power level is not corrected.

CalPod Assignments  

For each PNA port, select a CalPod module.

CalPod Setup  Starts the CalPod Setup dialog

Delete All CalPod Cal Sets  Deletes all recorrection Cal Sets and reinstates the Initialization Cal Set.



CalPod Setup dialog box help

To start this dialog, click CalPod Setup in the CalPod dialog box.

CalPod Serial Number  Type the CalPod module (without 'sn'), then click Add CalPod. The new module is added to the list of available CalPod modules.  (The list of available CalPod modules is limited to four entries when option 301 is the only PNA CalPod option.)

Serial # and CalPod Types

Shows the list of available CalPod modules.  A CalPod module type may be STANDARD or THERMAL.  A CalPod module will be listed as a STANDARD type unless two conditions are met: the PNA has option 302 and the thermal characterization data has previously been loaded into the PNA from a USB flash drive.


Test  Click to test the connection between the controller and the selected CalPod module. The message box displays the connection status and temperature for both Ambient and Thermal modules.  Only the Thermal module will apply test temperature for recorrection.

Delete  Removes the selected STANDARD CalPod module from the list.

To delete a THERMAL CalPod from the list:

  1. Navigate to the c:\e-trak\adapters\itm directory.

  2. Delete the .xml file associated with the CalPod serial number.

  3. Exit all CalPod dialog boxes and restart the CalPod dialog.

  4. The CalPod may now be removed using the Delete button.

About  Shows the CalPod software version information.

For more CalPod Setup information, see the CalPod web site: Click CalPod Controller Configuration.

CalPod Operator's Check

This program is provided as a convenience to help determine the operational status of each 855xxA Series CalPod and its associated CalPod Controller. While this check is not intended to be a complete test, it does check each unit enough to provide greater than 95% confidence that the CalPod is functioning properly.

Before running Op Check

The CalPod system must be installed and configured on the PNA. The PNA must have Option 301 or 302 installed.

See the CalPod User's Guide for instructions at:

Required equipment:

How to perform CalPod Operators Check

Click Utilities, then System, then Service, then CalPod, then OpCheck.

For PNA firmware version earlier than A.09.50, create a shortcut on the PNA desktop to C:\Program Files\Agilent\Network Analyzer\Service\CalPodOpChk.exe.  (To create a shortcut first navigate to the desired file, right click and hold on the file name, drag to the desktop, release and select “Create Shortcuts Here”.)

Click Setup Info to learn more about this dialog.

Also, click Cal Method or Connector for additional explanation for these areas.  


  1. Enter information in the “Configure” area.  

  2. Each time a 2-port cal is performed, the results are saved in a file.  The “Use Prior” selection uses the saved calibration.

  3. When the calibration connector type does not mate with the CalPod connectors, perform the calibration and then use adapters to connect to the CalPod module.

  4. Click Begin to start the Op Check.

  5. Follow the prompts in the gray box.

Op Check Results

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