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Operating Concepts
Modifying Calibration Kits
Modifying Calibration Kits
Modifying calibration kits is necessary only if unusual standards (such as in TRL*) are
used or the very highest accuracy is required. Unless a calibration kit model is provided
with the calibration devices used, a solid understanding of error-correction and the system
error model are absolutely essential to making modifications. You may use modifications to
a predefined calibration kit by modifying the kit and saving it as a user kit. The original
predefined calibration kit will remain unchanged.
Before attempting to modify calibration standard definitions, you should read Application
Note 8510-5A to improve your understanding of modifying calibration kits. The part
number of this application note is 5956-4352. Although the application note is written for
the 8510 family of network analyzers, it also applies to this network analyzer.
Several situations exist that may require a user-defined calibration kit:
• A calibration is required for a connector interface different from the four default
calibration kits. (Examples: SMA, TNC, or waveguide.)
• A calibration with standards (or combinations of standards) that are different from the
default calibration kits is required. (Example: Using three offset shorts instead of open,
short, and load to perform a 1-port calibration.)
• The built-in standard models for default calibration kits can be improved or refined.
Remember that the more closely the model describes the actual performance of the
standard, the better the calibration. (Example: The 7 mm load is determined to be
50.4 Ω instead of 50.0 Ω.)
Definitions
The following are definitions of terms:
• A "standard" (represented by a number 1-8) is a specific, well-defined, physical device
used to determine systematic errors. For example, standard 1 is a short in the 3.5 mm
calibration kit. Standards are assigned to the instrument softkeys as part of a class.
• A standard "type" is one of five basic types that define the form or structure of the
model to be used with that standard (short, open, load, delay/thru, and arbitrary
impedance); standard 1 is of the type short in the 3.5 mm calibration kit.
• Standard "coefficients" are numerical characteristics of the standards used in the model
selected. For example, the offset delay of the short is 32 ps in the 3.5 mm calibration kit.
• A standard "class" is a grouping of one or more standards that determines which of the
eight standards are used at each step of the calibration. For example, standard number
2 and 8 usually makes up the S
11
A reflection class, which for type-N calibration kits are
male and female shorts.
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