A four-port TRL calibration consists of six two-port TRL calibrations between six pairs of ports: 1-2, 1-3, 1-4, 2-3, 2-4, and 3-4. For example, when 1-2-3 ports are calibrated, three two-port TRL calibrations between ports 1-2, 1-3, and 2-3 must be performed.
The four-port TRL calibration with full set of standards is an accurate procedure but time-consuming. A simplified four-port TRL calibration can be performed instead. There are two options of the simplified four-port TRL calibration:
•The simplified four-port TRL calibration, which consists of three or more two-port TRL calibrations. The minimum number of three two-port TRL calibrations is required in case of the star topology of the calibration setup (with one common port), for example 1-2, 1-3, and 1-4. If the topology is not star, minimum of four two-port TRL calibrations is required.
•The simplified four-port TRL calibration, which consists of the combination of two two-port TRL calibrations and two THRU measurements. The two TRL calibrations are performed for pairs of nonadjacent ports, e.g. 1-2, and 3-4. The THRU measurements are performed for the remaining pairs of ports, e.g. 1-3, and 1-4. Two THRU measurements is the required minimum. To enhance the reliability of the calibration, up to four THRU measurements can be performed.
The THRU used in this calibration is the standard assigned TRL THRU class (See Calibration Standard Class Assignment). This should be the same standard, which is used in TRL calibration (LINE or FLUSH THRU), or a specific THRU.
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To open four-port TRL calibration submenu, use the following softkeys: Calibration > Calibrate > 4-Port TRL Cal |
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To toggle between normal and Multiline TRL calibration, click Multiline softkey. |
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To perform measurement of the TRL THRU, click Thru/Line: •For the calibration with the full set of standards, perform six measurements of the TRL THRU (THRU or LINE). •For the simplified calibration I, perform 3 measurements of the TRL THRU (THRU or LINE) with one common port. •For the simplified calibration II, perform 2 measurements of the TRL THRU (THRU or LINE) of 2 pairs of nonadjacent ports. Then perform (at least) 2 measurements of the THRU of the remaining port pairs. The instrument status bar will indicate Calibration in progress... when the measurement is in progress. On completion of the measurement, a check mark will appear in the left part of the softkey. Upon completion of the three measurements, the labels on the remaining softkeys change to Optional, what indicates that for simplified calibration I a sufficient number of measurements have been performed. Ignore such labels in case simplified calibration II is performed. |
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To perform measurement of the TRL REFLECT, click Reflect softkey. Then for the four ports repeat the following: •Connect a TRL REFLECT standard to the test ports in any order. •Perform measurement using Port n softkey. The instrument status bar will indicate Calibration in progress... when the measurement is in progress. On completion of the measurement, a check mark will appear in the left part of the softkey. |
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To perform measurement of the TRL LINE, click Line/Match softkey: •For the calibration with full set of standards, perform six measurements of the TRL LINE (LINE between the test ports or 2 LOADs to each port). •For the simplified calibration I, perform three measurements of the TRL LINE for the same pairs of ports as were used for measurements of TRL THRU (indicated with asterisks). •For the simplified calibration II, perform two measurements of the TRL LINE for the same pairs of nonadjacent ports as were used for measurements of TRL THRU. Note that asterisks cannot serve as a prompt! The instrument status bar will indicate Calibration in progress... when the measurement is in progress. On completion of the measurement, a check mark will appear in the left part of the softkey. Upon completion of the two or three measurements, the labels on the remaining softkeys change to Optional, what indicates that for simplified calibration a sufficient number of measurements have been performed. |
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To complete the calibration procedure, click Apply softkey. This will activate the process of calibration coefficient table calculation and saving it into the memory. The error correction function will also be automatically enabled. |
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System correction will turn automatically off when Apply softkey is pressed to perform TRL calibration (See System Correction Setting). |
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To clear the measurement results of the standard, click Cancel softkey. This softkey does not cancel the current calibration. To disable the current calibration, turn off the error correction function (See Error Correction Disabling). |
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The calibration status can be checked in channel status bar (See General error correction status table) or in trace status field (See Trace error correction status table). |
