VNA concepts and features
R&S
®
ZNL/ZNLE
252
User Manual 1178.5966.02 ─ 19
9.5.1.4
TOSM and UOSM calibration
TOSM
A TOSM (Through – Open – Short – Match) calibration requires the same standards as
the one path two ports calibration, however, all measurements are performed in the for-
ward and reverse direction. TOSM is also referred to as SOLT (Short – Open – Load =
Match – Through) calibration. The four standards are used to derive 6 error terms for
each signal direction:
●
In addition to the source match and reflection tracking error terms provided by the
one-path two-port calibration, TOSM also provides the load match.
●
The directivity error is determined at all source ports.
●
The transmission tracking is determined for each direction.
TOSM calibration is provided for 2-port measurements. A 2-port TOSM calibration
requires 7 standard measurements (3 one-port standards at each port and a Through
between the two ports). The Through must be measured in both directions, so the
number of standard measurements (calibration sweeps) is 8. The calibration provides
10 error terms (no isolation terms are available).
Manual TOSM calibration supports
Complementary isolation measurement
UOSM: TOSM with unknown Through
The analyzer can perform a TOSM calibration with any 2-port network serving as
through connection, as long as it fulfills the reciprocity condition S
21
= S
12
. The modified
TOSM calibration is referred to as UOSM (Unknown through – Open – Short – Match)
calibration. It can be selected as follows:
●
If different connector types are assigned to the test ports, the analyzer automati-
cally replaces TOSM by UOSM.
[The network analyzer supports different connector types at its test ports to mea-
sure DUTs with different port connectors. ]
●
If the same connector types are used but an appropriate Through standard is not
defined, the analyzer also replaces TOSM by UOSM.
After acquiring the calibration sweep data for the unknown through, the analyzer auto-
matically determines its delay time/transmission phase.
Manual UOSM calibration is not supported on a R&S
ZNL3|4|6 or R&S
ZNLE3|4|6 that
is equipped with the old VNA board (order no 1323.0070). These instruments only sup-
port
UOSM calibration.
9.5.1.5
TRL calibration
A TRL (Through – Reflect – Line) calibration requires the two-port standards Through
and Line, which are both assumed to be ideally matched. The Through must be loss-
Calibration
