Concepts and Features
R&S
®
ZNB/ZNBT
187
User Manual 1173.9163.02 ─ 53
●
The DC loss c is zero except for wave quantities and for S-parameters and ratios
with maximum dB magnitude larger than –0.01 dB.
●
"Auto Length and Loss" for a wave quantity centers the corrected dB magnitude as
close as possible around 0 dBm.
●
"Auto Length and Loss" for S-parameters and ratios centers the corrected dB mag-
nitude as close as possible around 0 dB.
The resulting offset parameters are displayed in the CHANNEL – [OFFSET
EMBED] >
"Offset" softtool tab.
Auto Length and Loss for balanced ports
The "Auto Length and Loss" function can be used for balanced port configurations as
well. If the active test port is a balanced (logical) port, then the same offset parameters
must be assigned to both physical ports that are combined to form the logical port. If
different offset parameters have been assigned to the physical ports before, they are
both corrected by the same amount.
5.6.1.5
Fixture Compensation
"Fixture Compensation" is an automated length offset and loss compensation for test
fixtures. The analyzer performs a one-port reflection measurement at each port,
assuming the inner contacts of the test fixtures to be terminated with an open or short
circuit.
"Fixture Compensation" complements a previous system error correction and replaces
a possible manual length offset and loss correction. For maximum accuracy, it is rec-
ommended to place the reference plane as close as possible towards the outer test fix-
ture connectors using a full n-port calibration. The "Fixture Compensation" is then car-
ried out in a second step, it only has to compensate for the effect of the test fixture con-
nections.
The following features can further improve the accuracy of the fixture compensation:
●
"Direct Compensation" provides a frequency-dependent transmission factor
(instead of a global electrical length and loss).
●
"Open and Short" causes the analyzer to calculate the correction data from two
subsequent sweeps. The results are averaged to compensate for errors due to
non-ideal terminations.
Auto Length and Loss vs. Direct Compensation
"Auto Length and Loss" compensation is a descriptive correction type: The effects of
the test fixture connection are traced back to quantities that are commonly used to
characterize transmission lines.
Use this correction type if your test fixture connections have suitable properties in the
considered frequency range:
●
The electrical length is approximately constant.
●
The loss varies due to the skin effect.
Offset Parameters and De-/Embedding
