R&S
®
ZVL
System Overview
Calibration Overview
Quick Start Guide 1303.6538.62-01
96
3.3.2.3 One-Path Two-Port Calibration
A one-path two-port calibration combines a full one-port calibration with a transmission
normalization, so it 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:
E
The short and open standards are used to derive the
source match
and the
reflection tracking error
terms at the source port.
E
The match standard is used to derive the
directivity error
at the source port.
E
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) and 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 to be measured and the DUT
is well matched, especially at the load port.
3.3.2.4 TOSM
Calibration
A TOSM (Through – Open – Short – Match) calibration requires the same standards as
the one-path two-port calibration, however, all measurements are performed in the
forward 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:
E
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
.
E
The
directivity
error is determined at both source ports.
E
The
transmission tracking
is determined for each direction.
The number of required standard measurements and of error terms for 2-port
measurements is shown in the following table.
Number of ports
Number of standards to
be connected
Number of standard
measurements
Number of error
terms
2
2 * 3
+1 = 7
2 * 3
+2 * 1 = 8
2 * 3
+ 2 * 2 = 10
An open, through and match measurement is required at each port; in addition, a
through must be measured between the two ports and in both directions.
The analyzer automatically performs each through measurement in both directions, so
the number of connected standards is smaller than the number of measurements.
