R&S ZNA26 - Page 164

Concepts and features
R&S
®
ZNA
164User Manual 1178.6462.02 ─ 20
A reflection OSM calibration is more accurate than a normalization but is only applica-
ble for reflection measurements.
4.5.1.3 One Path Two Ports Calibration
A one path two ports calibration combines a reflection OSM (full one-port) calibration
with a transmission normalization. The fully calibrated port is termed the node port.
This calibration type requires a Short, an Open and a Match standard to be connected
to a single test port plus a Through standard between this calibrated source port and
the other load ports. The four standard measurements are used to derive the following
error terms:
●
The Short and Open standards are used to derive the source match and the reflec-
tion tracking error terms at the source port.
●
The Match standard is used to derive the directivity error at the source port.
●
The Through standard provides the transmission tracking error terms.
For calibration of two ports, a one-path two-port calibration requires only four standards
to be connected (instead of 7 for a full two-port TOSM calibration). It is suitable when
only the forward (e.g. S
11
and S
21
) or reverse S-parameters (e.g. S
22
and S
12
) are nee-
ded, and if the DUT is well matched, especially at the load port.
A one-path two-port calibration is also the best calibration method for test setups with
unidirectional signal flow, e.g. a pulsed measurement using an external generator.
4.5.1.4 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 arbitrary n-port measurements (n>1). The number of
required standard measurements and of error terms increases as shown in the follow-
ing table.
Calibration