Microstrip Line Sim Difference between model and EM result in ADS

There can be many mistakes in measurement (i.e. connectors, VNA port calibration)) and simulation.

From your S11 plot, it seems that electrical length is rather different. To avoid trivial mistakes in VNA port calibration, measure one coax connector which you short directly at the PCB side. Make sure that this appears as a short in Smith chart, with no additional phase offset.

volker@muehlhaus said:

There can be many mistakes in measurement (i.e. connectors, VNA port calibration)) and simulation.

From your S11 plot, it seems that electrical length is rather different. To avoid trivial mistakes in VNA port calibration, measure one coax connector which you short directly at the PCB side. Make sure that this appears as a short in Smith chart, with no additional phase offset.

Click to expand...

Thanks. but I only used simulation tool to run the simulation instead of the real measurement.

edwardev said:

Thanks. but I only used simulation tool to run the simulation instead of the real measurement.

Click to expand...

I see ... I was confused because you didn't follow the usual workflow for Momentum model results as an emModel view (link), but this doesn't explain your differences.

For sure, this difference is not expected, so I recommend that you start all over again. My best guess is that you have compared to some outdated Momentum results obtained with other geometry parameters (width w is a tuned variable). If you use the emModel workflow from my link above, you don't need intermediate S2P files, and reduce the risk of comparing apples to oranges.