Concepts and features
R&S
®
ZNA
203
User Manual 1178.6462.02 ─ 20
2. In the Channel – [Offset
Embed] > "Offset" softtool tab, select "Auto Length".
The delay is displayed in the "Delay" field, the cable length (depending on the
"Velocity Factor") in the "Mech. Length" field.
It is also possible to determine cable lengths using a transmission measurement. Note
that "Auto Length" always provides the
single
cable length and the delay for propaga-
tion in
one
direction.
The analyzer provides alternative ways for delay measurements:
1. Measure the reflection factor and select Trace – [Format] > "Delay".
This yields the delay for propagation in forward and reverse direction and should
be approx. twice the "Auto Length" result. For transmission measurements, both
results should be approx. equal.
2. Measure the reflection factor and select Trace – [Format] > "Phase". Place a
marker to the trace and activate Trace – [Trace
Config] > "Trace Statistics" >
"Phase/El Length".
This yields the delay in one direction and should be approx. equal to the "Auto
Length" result.
The measurement results using trace formats and trace statistics functions depend on
the selected delay aperture and evaluation range. "Auto Length" is particularly accu-
rate because it uses all sweep points. For non-dispersive cables, aperture and evalua-
tion range effects are expected to vanish.
Use Trace – [Marker] > "Set by Marker" > Zero Delay at Marker to set the delay at a
special trace point to zero.
Preconditions for Auto Length, effect on measured quantities and exceptions
"Auto Length" is enabled if the measured quantity contains the necessary phase infor-
mation as a function of frequency, and if the interpretation of the results is unambigu-
ous:
●
A frequency sweep must be active.
●
The measured quantity must be an S-parameter, ratio, wave quantity, a converted
impedance or a converted admittance.
The effect of "Auto Length" on S-parameters, wave quantities and ratios is to eliminate
a linear phase response as described above. The magnitude of the measured quantity
is not affected. Converted admittances or impedances are calculated from the corre-
sponding "Auto Length" corrected S-parameters. Y-parameters, Z-parameters and sta-
bility factors are not derived from a single S-parameter, therefore "Auto Length" is dis-
abled.
Auto Length for logical ports
The "Auto Length" function can be used for balanced port configurations as well. If the
active test port is a logical port, then the same length offset must be assigned to both
physical ports that are combined to form the logical port. If different length offsets have
Offset parameters and de-/embedding
