VNA Concepts and Features
R&S
®
ZNL/ZNLE
240
User Manual 1178.5966.02 ─ 07
If the reference impedances are identical and real this common resistance value is
used as reference resistance of the Touchstone option line. Otherwise the value 50 Ω
is used.
●
Common Target Impedance
For multi-port S-parameters, the reference resistance of the Touchstone option line
is taken as common target impedance and the data is renormalized to the common
target impedance, regardless of the port reference impedances. Thus in case of
ambiguous port reference impedances the data is always renormalized to 50 Ω.
●
Port Reference Impedance
The
Chapter 8.3.6, "Reference Impedances"
on page 227 of the individual ports
are used as target impedances for the renormalization. The target impedances are
listed in a comment line in the Touchstone file. If the related ports use different ref-
erence impedances, an additional comment with a warning is added that the
Touchstone option line contains a non-matching reference resistance (see example
below).
Note
that when reimporting this type of file into standard applications (including the
R&S
ZNL/ZNLE itself), the reference resistance from the Touchstone option line is
used and the impedance system underlying the data is not interpreted correctly.
Example: Renormalization comments
!The following Port Impedance Renormalization has been used when saving the data.
!PortZ Port1:50+j0 Port2:70+j0
!Note: The Port Impedances differ from the reference impedance of this file.
! While reading the file the reference impedance value of the option line above
! is always used.
Touchstone files cannot be used to export mathematical traces.
8.4.2.2
ASCII (*.csv) Files
An ASCII file contains a header and the actual trace data:
freq;reTrc1_S21;imTrc1_S21;reMem2[Trc1]_S21;imMem2[Trc1]_S21;
300000.000000;0.000000;0.000000;0.000000;0.000000;
40499497.487437;0.000000;0.000000;0.000000;0.000000;
80698994.974874;0.494927;-0.065174;0.500833;-0.074866;
120898492.462312;0.497959;-0.111724;0.488029;-0.107375;
...
The header consists of the following data elements:
●
<Stimulus> stimulus variable: freq for Frequency sweep, time for Time sweep, trig-
ger for CW Mode sweep.
●
<reTrace1> first response value of first trace: re<Trace_Name>,
mag<Trace_Name> or db<Trace_Name> for output format Re/Im, lin. Mag-Phase
Operations on Traces
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