EM Simulation for Lange Coupler

Hi,

I am working on a lange coupler. I ran EM in 3 ways to compare results: Sonnet, ADS momentum and FEM. But the responses are so different for the same Lange Coupler. I am not sure which one to trust.

For example, ADS momentum shows perfect coupling but Sonnet shows no coupling. ADS momentum and Sonnet show good phase response but FEM shows crazy phase response.

Any idea why?

From long experience im EM tool support: The biggest error source in EM simulation is the user. We don't know your models, and how familiar you are with these tools, so how can we know what model is correct?

These massive differences that you report sound like modelling mistakes. To get started, look at current densities and check if they make physical sense.