The following is discussed in this topic:
What Is Measurement Calibration?
Calibration removes one or more of the systematic errors using an equation called an error model. Measurement of high quality standards (for example, a short, open, load, and thru) allows the analyzer to solve for the error terms in the error model. See Measurement Errors.
You can choose from different calibration types, depending on the measurement you are making and the level of accuracy you need for the measurement. See Select a Calibration Type.
The accuracy of the calibrated measurements is dependent on the quality of the standards in the calibration kit and how accurately the standards are modeled (defined) in the calibration kit definition file. The calibration-kit definition file is stored in the analyzer. In order to make accurate measurements, the calibration-kit definition must match the actual calibration kit used. To learn more, see Accurate Calibrations.
Calibration Wizard provides the different calibration methods used in the VNA. See Calibration Wizard.
There are quick checks you can do to ensure your measurement calibration is accurate. To learn more see Validity of a Measurement Calibration
If you make your own custom-built calibration standards (for example, during in-fixture measurements), then you must characterize the calibration standards and enter the definitions into a user modified calibration-kit file. For more information on modifying calibration kit files, see Calibration Standards.
Note: Instrument Calibration is ensuring the analyzer hardware is performing as specified. This is not the same as measurement calibration.
It is impossible to make perfect hardware that would not need any form of error correction. Even making the hardware good enough to eliminate the need for error correction for most devices would be extremely expensive.
The accuracy of network analysis is greatly influenced by factors external to the network analyzer. Components of the measurement setup, such as interconnecting cables and adapters, introduce variations in magnitude and phase that can mask the actual response of the device under test.
The best balance is to make the hardware as good as practically possible, balancing performance and cost. Calibration is then a very useful tool to improve measurement accuracy.
Conditions Where Calibration Is Suggested
Generally, you should calibrate for making a measurement under the following circumstances:
You want the best accuracy possible.
You are adapting to a different connector type or impedance.
You are connecting a cable between the test device and an analyzer test port.
You are measuring across a wide frequency span or an electrically long device.
You are connecting an attenuator or other such device on the input or output of the test device.
If your test setup meets any of the conditions above, the following system characteristics may be affected:
Amplitude at device input
Frequency response accuracy
Directivity
Crosstalk (isolation)
Source match
Load match
ECal is a complete solid-state calibration solution. It makes one port (Reflection), full two and three-port calibrations fast and easy. See Using ECal.
It is less prone to operator error.
The various standards (located inside the calibration module) never wear out because they are switched with PIN-diode or FET switches.
The calibration modules are characterized using a TRL-calibrated network analyzer.
ECal is not as accurate as a good TRL calibration.
For information about ordering ECal modules, see Analyzer Accessories or contact your Keysight Support Representative