Anritsu VectorStar MN469 C Series, Руководство по обслуживанию, Страница: 24 / 78

3-5 S-Parameters Measurements Verification Chapter 3 — Performance Verification
3-4 PN: 10410-00730 Rev. D MN469xC Series Multiport Test Set MM
3-5 S-Parameters Measurements Verification
The following test verifies S parameter measurement capabilities of the MS4640A/B VNA, MN469xC Test Set,
calibration kit, test port cable, and any required adapters as a system by analyzing the measurement of
artifacts that are traceable to national standards laboratories. The procedures are automated by using the
MS464XX System Verification software, which can be found on the USB memory device that is supplied with
each 3668-1 or 3669B-1 Verification Kit.
The MS464XX System Verification software guides the user to perform a full 12 Term calibration on the 4-port
VNA System by using the appropriate calibration tees, to measure the S parameters of the impedance transfer
standards in the verification kit, and to verify that the measured values are within the specified measurement
uncertainty limits.
The impedance transfer standards that are contained in the verification kit are:
• 20 dB Attenuation Standard
• 50 dB Attenuation Standard
• 50 ohm Air Line Standard
• 25 ohm Mismatch (Beatty) Standard
The devices in the verification kit are selected based on their ability to stress the envelope of possible
measurement parameters while still providing a very stable and repeatable behavior. The key attribute of the
devices is that of long term stability.
Verification Result Determination
The software verification process compares the measured S-parameter data of the impedance transfer
standards against the original standard (characterization) data for those devices that was obtained using the
Factory Standard MS464XX Vector Network Analyzer (at Anritsu).
The Factory Standard MS464XX system is traceable to NIST through the impedance Standards of the Anritsu
Calibration laboratory. These standards are traceable to NIST through precision mechanical measurements,
NIST-approved microwave theory impedance derivation methods, and electrical impedance comparison
measurements.
At each frequency point, the verification measurement is compared to the characterization measurement in the
context of the uncertainties. If the delta between the two measurements is consistent with the uncertainty
window, the measurement is considered acceptable at that point.
The metric of comparison, termed En, is a check to see if the measurement differences are consistent with the
uncertainty windows of both the characterization and the verification measurements. The quantity is shown in
the formula below:
where:
• The numerator contains the magnitude or phase of S-parameters measured during characterization (by
Anritsu) and during verification (by the user).
• The denominator contains the respective uncertainties.
These uncertainties are calculated based on the VNA, the calibration kit, and repeatability. If this quantity En
is less than 1, then the measurements during the two phases are within the overlap of the uncertainties and
one can consider the measurements “equivalent” and, in some sense, verified.