Concepts and features
R&S
®
ZNA
176
User Manual 1178.6462.02 ─ 20
The following additional parameters are used:
●
Characteristic impedance: Z
0
(characteristic impedance of the connector type)
●
Loss: 0 dB / sqrt(GHz) or (0 GΩ / s) in Keysight mode
●
All inductance and capacitance parameters are set to zero.
4.5.2.3
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 4-8: 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
ZNA can acquire correction data for up to 20 positions.
Calibration
