The group has been focused on SOLT or so called SOLM (match) for calibration. However, for various reasons the TRL; Thru, Reflect, Line calibration algorithm would be advantageous. Fabrication of such a kit usually requires at least 3 lines to be built plus one fixture piece and microstrip is not difficult using a straight edge and an Exacto blade knife! The TRL lends itself to NON INSERTION components. In another words, non coaxial elements. Just a thought and the copy below hints to the benefits.
From Keysight:
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A vector network analyzer requires that a measurement calibration be performed before error-corrected measurements can be made. For two-port measurements, the calibration algorithm used will determine the appropriate calibration kit, known either as SOLT or TRL/TRL*.
Traditional full two calibration calibration typically utilizes three impedance and one transmission standards to define the calibrated reference plane. These standards, typically a Short, Open, Load, and Thru, make up the SOLT calibration kit.
Another two port calibration type utilizes a minimum of three standards to define the calibrated reference plane. The measured parameters of the Thru, Reflect, and Line standards in a TRL/TRL* calibration kit provides the same information as a SOLT calibration via a different algorithm.
Depending on the availability of calibration standards and the functionality of the network analyzer, one may use either calibration kit.
In many non-coaxial , SOLT calibration standards are difficult, if not impossible, to build. The non-availability of calibration standards in proprietary or unique coaxial connectors also benefit from the TRL/TRL* calibration method.
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