Concepts and Features
R&S
®
ZNC
71
User Manual 1173.9557.02 ─ 13
3.5.1.2
Reflection OSM Calibration
A reflection OSM (full one-port) calibration requires a Short, an Open and a Match stand-
ard to be connected to a single test port. The three standard measurements are used to
derive all three reflection error terms:
●
The Short and Open standards are used to derive the source match and the reflection
tracking error terms.
●
The Match standard is used to derive the directivity error.
A reflection OSM calibration is more accurate than a normalization but is only applicable
for reflection measurements.
3.5.1.3
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 cal-
ibration 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 a second load
port. 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 reflection
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 term.
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 needed, and if the DUT is well
matched, especially at the load port. It is also the best calibration method for test setups
with unidirectional signal flow, e.g. a pulsed measurement using an external generator.
3.5.1.4
TOSM and UOSM Calibration
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 both 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).
Calibration
