Altair Feko: How does adding or restoring loads for an S-parameter configuration affect the load setup for the next configuration
Altair EmployeeThis article summarises by means of an example how the settings of an S-parameter configuration affects the load setup for the next configuration (standard or S-parameter).
Example: A model has three ports where port 1 has a load of 10 Ohm. There are two S-parameter configurations defined in the model that use port 1, port 2 and port 3. The system/reference impedance for all three S-parameter configurations are 50 Ohm.
Diagram showing the model port set up.
Note: The default option in CADFEKO when adding an S-parameter configuration is to add port impedance to the existing loads and only has the Restore loads after calculation check box. This corresponds with Scenario 1 and Scenario 2 below.
The Create S-Parameters dialog in CADFEKO.
Scenario 1
For the first S-parameter configuration, the following options are selected at the SP card in EDITFEKO:
The port S-parameter reference load of 50 Ohm is added to the existing user-defined loads of 10 Ohm at port 1, resulting in 60 Ohm. Port 2 and Port 3 will have 50 Ohm loads.
After executing the S-parameter configuration, the load at port 1 is restored to its prior state of 10 Ohm (the S-parameter reference loads that were added in this S-parameter configuration are removed).
The load at port 1 will be 10 Ohm for the standard- or S-parameter configuration that follow. Port 2 and port 3 will be restored to its prior state of no loads.
Scenario 2
For the first S-parameter configuration, the following options are selected at the SP card in EDITFEKO:
The port S-parameter reference load of 50 Ohm is added to the existing user-defined loads of 10 Ohm at port 1, resulting in 60 Ohm. Port 2 and Port 3 will have 50 Ohm loads.
After executing the S-parameter configuration, the S-parameter reference loads are maintained.
The load at port 1 will be 60 Ohm for the standard- or S-parameter configuration that follow. Port 2 and port 3 will maintain the S-parameter reference loads of 50 Ohm.
Scenario 3
For the first S-parameter configuration, the following options are selected at the SP card in EDITFEKO:
The port S-parameter reference loads are not added but replaces the existing user-defined loads of 10 Ohm at port 1, resulting in 50 Ohm. Port 2 and Port 3 will have 50 Ohm loads.
After executing the S-parameter configuration, the load at port 1 is restored to its prior state of 10 Ohm (the S-parameter reference loads that were added in this S-parameter configuration are removed).
The load at port 1 will be 10 Ohm for the standard- or S-parameter configuration that follow. Port 2 and port 3 will be restored to its prior state of no loads.
Scenario 4
For the first S-parameter configuration, the following options are selected at the SP card in EDITFEKO:
The port S-parameter reference loads are not added but replaces the existing user-defined loads of 10 Ohm at port 1, resulting in 50 Ohm. Port 2 and Port 3 will have 50 Ohm loads.
After executing the S-parameter configuration, the S-parameter reference loads are maintained.
The load at port 1 will be 50 Ohm for the standard- or S-parameter configuration that follow. Port 2 and port 3 will maintain the S-parameter reference loads of 50 Ohm.