VNA Concepts and Features
R&S
®
ZNL/ZNLE
251
User Manual 1178.5966.02 ─ 07
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Loss: 0 dB / sqrt(GHz) or (0 GΩ / s) in Agilent mode
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All inductance and capacitance parameters are set to zero.
8.5.2.3
Sliding Match Standards
The Sliding Match is a one-port standard consisting of an air line with a movable, low-
reflection load element (sliding load). This standard is used because a no perfect
Match is available over a wide frequency range. However, a series of measurements at
a given frequency with equal mismatch and varying phase yields reflection factors that
are located on a circle in the Smith chart. The center of this circle corresponds to per-
fect match. The network analyzer determines and further corrects this match point fol-
lowing I. Kása's circle-fitting algorithm.
To obtain the reflection coefficient for a perfectly matched calibration standard, the Slid-
ing Match must be measured at least at 3 positions which should be unequally spaced
to avoid overlapping data points. Increasing the number of positions to 4 to 6 can
improve the accuracy. Moreover, using the predefined load positions of the standard is
recommended.
Figure 8-2: Sliding Match: GUI representation
A calibration is valid (and can be applied to the calibrated channel) if either the Match
or three positions of the Sliding Match have been measured. However, it is often desir-
able to acquire calibration data from both standards.
The R&S
ZNL/ZNLE can acquire correction data for up to 20 positions.
The analyzer combines the data in an appropriate manner:
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The Match results are used up to the lower edge of the specified frequency range
of the Sliding Match (Min Freq).
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The Sliding Match results are used for frequencies above the Min Freq. In general,
the Sliding Match provides better results than the Match within its specified fre-
quency range.
Calibration
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