I have simulated S parameters of a PCB board from 0-10 GHz. The measurement data is agreeable with the simulation data up to 2 GHz. But after 2 GHz, measurement and simulation data are not that much close. I am assuming my simulation is correct. So can anyone please answer why the higher frequency affect the measurement? Or what may be the reason that simulation and measurement are not that much agreeable in high frequency?
Your simulation model is correct that is why it is giving you correct solution at lower frequency.
The problem is mesh definition for higher frequencies you need to define more dense and more refine mesh.
Because HFSS and CST both solve the model mathematically at the discrete points defined by mesh with the assumption that wavelength >> mesh cell.
So as the frequency goes high the above assumption does not remain valid resulting in inaccurate solutions.
Since you are getting correct results at lower frequency so just define more refined means more dense mesh and i hope the problem will be resolved
i suggest to use CST , namely for gridding the mesh, the results by subgridding is more accurate
i hop to be helpful
Can you please further explain how to use this sub girding and what it had the relationship with the problem.
As the issue in hand is inaccurate results at higher frequency. Please explain