Define an S-parameter configuration and add it to the model.
Add an S-parameter configuration using one of the following workflows:
On the Request tab, in the
Configurations group, click the S-parameter Configuration icon.
In the configuration list, click the icon. Select S-parameter Configuration from the
menu .
In the Port column, from the drop-down list, select the port.
In the Properties column, specify the following:
For waveguide ports, specify the type (TE1 / TM2/ TEM3), indices and rotation of the
mode.
For ports other than waveguide and FEM modal ports, specify the reference impedance. If no impedance is
specified, a default reference impedance of 50 Ohm is used.
In the Active column, select the check box to use the
port as a “source” (else the port is only a “receiving” or “sink”
port).
Note: For example, if a Port1 and Port2 is
defined, but only Port1 is active, only S11
and S21 are calculated.
[Optional] Select the Export S-parameters to Touchstone
file check box to export the S-parameters to a .snp
file.
For each S-parameter configuration, a separate Touchstone file is created.
The file name is in the form
<FEKO_base_filename>_<requestname>(k).snp where:
FEKO_base_filename
file name of the model
requestname
request name
n
number of ports
k
a counter (integer) to distinguish between the results of
multiple requests with the same name and the same number of
ports.
Note:
Feko does not normalise the S-parameter
values to a global reference impedance when exporting the S-parameters
to a Touchstone file. The values are referenced to the impedance
specified on each port.
CAUTION:
Some industry tools that use the Touchstone format often
assume that all values are referenced to a common impedance. When exporting
S-parameters for use in an industry tool that supports only a single
reference impedance, specify the reference impedance for each port to ensure
the correct interpretation.
During the calculation of S-parameters, the specified reference impedances
are added as loads to the ports. These loads remain in place after the S-parameter
calculation. If the loads are removed once the S-parameter calculation is complete
and there are subsequent output requests, such as near fields, the full matrix
computation and LU decomposition steps will be repeated for the MoM solution method. This is typically the most
time-consuming step in the analysis. It must be noted that should near fields be
requested, and the loads remain, the near fields will be lower in magnitude due to
the losses in the loads.
[Optional] Select the Restore loads after calculation
check box to remove the loads once the S-parameter calculation is
complete.
In the Label field, add a unique label for the
request.
Click Create to request the S-parameter results
and to close the dialog.
The port numbers in an S-parameter solution are indexed
based on the order of appearance in the port list on the Create
S-parameters dialog, and not according to the label of the selected
port.