Reply To: Ansys HFSS, Lumped port impedance affects Z-parameters

[Gia]

 

1) Consider how you would make the connection of the physical device to a physical VNA. – A lumped port is essentially a connection to a virtual-VNA where the characteristic impedance of the virtual-VNA is the same characteristic impedance that is defined in the lumped port settings. – This is why the lumped ports default to 50 ohms. – If the physical VNA is not connected to the 2nd port when performing the physical measurement, and it is simply terminated with a 180 ohm load, then to make a direct comparison of measurement vs. simulation of S11, you can replace port 2 in HFSS with a ‘LumpedRLC’ boundary set to 180 ohms and export as a 1 port touchstone file.

2) In a similar way as the lumped ports in HFSS, the symbols used to represent your ports in your circuit model should also have a setting for their reference characteristic impedance. You should see similar results for your S11 for the above case as if you were to use a 180 ohm port impedance for your 2nd lumped port while keeping the default 50 ohm impedance for the virtual ports in the circuit schematic.

There is also a built-in Circuit tool with the Ansys Electronics Desktop that is similar to ADS, here are some YouTube videos on the topic:

Steps to Co-simulation Using Ansys HFSS and Circuit

PIN Diode simulation in Ansys HFSS + Circuit co-simulation | Part 1