Date: Fri, 29 Mar 2024 12:42:40 +0000 (GMT)
Message-ID: <1814044382.193.1711716160775@[172.30.0.157]>
Subject: Exported From Confluence
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Imported S-parameter Data File Looks Different When Plotted in A=
WRDE vs. Original Tool
Imported S-parameter Data File Looks Different When Plotted in AWRD=
E vs. Original Tool
Problem
An S-parameter data file is generated outside of AWRDE, and is later imp=
orted into a project in AWRDE. However, when plotted, the S-parameter=
s do not look the same as they did in the tool where they originated.
Solution
This is a normalization issue.
- If the S-parameter measurement in Microwave Office specifies the data f=
ile as the Data Source Name (i.e. if you are plo=
tting the S-parameters directly from the file, not from a schematic where t=
he file is used), then the measurement will assume 50 Ohm terminations at a=
ll ports. To see the data when the ports are terminated in an im=
pedance other than 50 Ohms, the imported S-parameter data file must be plac=
ed in a schematic as a SUBCKT block, and terminated with ports that have th=
e desired Z value.
- When the data file is generated, the S-parameter data must be normalize=
d to a constant real system reference impedance, ideally 50 Ohms. Som=
e EM simulators write unnormalized data in a format that meets the Touchstone 1.1 format specification, but according =
to that format, will be interpreted as being normalized to 50 Ohms. I=
n these files, the frequency dependent complex reference impedance for each=
port is written as a comment line that is completely ignored. Such d=
ata files will import without error, but will not behave like they did in t=
he tool that generated them.
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