VNA Concepts and Features
R&S
®
ZNL/ZNLE
262
User Manual 1178.5966.02 ─ 07
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
been assigned to the physical ports before, they are both corrected by the same
amount.
8.6.1.4
Auto Length and Loss
The "Auto Length and Loss" function ([Offset Embed] > "One Way Loss" > "Auto
Length and Loss") determines all offset parameters such that the residual group delay
of the active trace (defined as the negative derivative of the phase response) is mini-
mized and the measured loss is minimized as far as possible across the entire sweep
range.
"Auto Length and Loss" involves a two-step procedure:
●
An "Auto Length" correction modifies the phase of the measured quantity, minimiz-
ing the residual group delay. The magnitude of the measured quantity is not affec-
ted.
●
The automatic loss correction modifies the magnitude of the measured quantity,
leaving the (auto length-corrected) phase unchanged.
Preconditions for Auto Length and Loss, effect on measured quantities and
exceptions
"Auto Length and Loss" is enabled if the measured quantity contains the necessary
phase information as a function of the frequency, and if the interpretation of the results
is unambiguous:
●
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 and Loss" on S-parameters, wave quantities and ratios is to
eliminate a linear phase response and account for a loss as described above. Conver-
Offset Parameters and Embedding
www.allice.de
Allice Messtechnik GmbH
