Concepts and Features
R&S
®
ZNB/ZNBT
153
User Manual 1173.9163.02 ─ 53
A one-path two-port calibration is also the best calibration method for test setups with
unidirectional signal flow.
5.5.1.4
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.
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
3
3 * 3
+ 2 + 1 = 12
3 * 3
+2 * (2 + 1) = 15
3 * 3
+ 2 * 2 * 3 = 21
4
4 * 3
+3 + 2 + 1 = 18
4 * 3
+2 * (3 + 2 + 1) = 24
4 * 3
+ 2 * 2 * 6 = 36
*) No isolation terms are available.
An Open, Through and Match measurement is required at each port; in addition, for a
full TOSM, a Through must be measured for every directed port pair. Therefore the
total number of standard measurements for an n-port TOSM calibration is
3n + n (n-1)
= n (n+2)
. However, this number can be significantly decreased without losing too
Chapter 5.5.1.11, "Full n-Port Calibration with Reduced Number of
The analyzer automatically performs each through measurement in both directions, so
the number of connected standards is smaller than the number of measurements.
Manual TOSM calibration supports
Complementary Isolation Measurement
Calibration
