For best VNA measurement results with the PXIe-5842 VST with S-Parameters, you should always apply a valid measurement calibration dataset, or calset, to your measurements. Refer to the guidelines for when to perform VNA measurement calibration and for VNA measurement calibration best practices.

  • Always apply a measurement calibration that reflects your test setup to VNA measurements; if you have saved a calset for a given configuration, ensure that it is applied to the measurement
  • NI recommends using high-performance, phase-stable RF test port cables; NI offers several suitable cables to choose from, including the Sucoflex 526S (NI part number 137445-01)
  • NI recommends configuring the PXIe-5842 VST with S-Parameters during measurement calibration with identical settings to those you will use during measurement
  • The frequency list you define determines both the frequencies used for the VNA measurement calibration and the actual measurement and defines only those frequencies specifically included in the list.
  • For best measurement calibration results:
    • Ensure that all connectors of the PXIe-5633, CAL-5501, and all cables that connect the two are completely free of debris and are undamaged
    • Keep the physical layout of your test system, such as the orientation of cables, as consistent as possible between measurement calibration and measurement and between different measurements
    • If your test fixture includes any adapters or more complex elements between the PXIe-5842 VST with S-Parameters and the calibration standards or DUT, you can characterize and de-embed them to remove their influence from measurement calibration and VNA measurements
  • Perform a new measurement calibration in any of the following situations:
    • If any new fixturing, such as new connectors or cables, is replaced or added between the PXIe-5842 VST with S-Parameters and the DUT
    • If you change the set of frequencies or any attenuation settings used for your VNA measurements to any frequencies or attenuation settings not already included in the calset
    • If highest accuracy is required:
      • If you change the IF bandwidth for your measurements
      • If the ambient temperature in the test environment or the onboard temperature of the instrument changes by an amount you deem significant enough
      • To account for drift, if an amount of time you deem significant enough elapses since the previous measurement calibration