I’m simulating simple coaxial structures in CST HF-solver in frequency domain. My goal is to extract the S-Parameters, convert them to T-Parameters and thus getting a transfer function for the voltage. Doing so I obtain very unrealistic results in lower frequencies below 10 kHz. All graphs are showing many minima and maxima (like resonances) ad sometime switching the sign rapidly.

Instead, when using the CST Design Studio (“schematic” tab) and performing an AC-simulation task with the 3D-model the graphs are looking much more as analytically expected! Obviously there is a difference between HF-FD-solver and AC-simulation task. That confusing me.

May you can give me further information about AC-simulation task (or the whole Design Studio in total) to help me understand how deals with S-Parameters and AC-tasks. So far I already studied the help pages as well as the “CST Studio Suite - Circuit Simulation and SAM (System Assembly and Modeling).pdf”. May there are further sources of information available?

Thanks in advance

Tobin

CST Studio Suite ​​​​​​​