Aakriti Srivastava

I am using HFSS driven terminal solution type.

Radiation boundary is assigned to the dielectric material surrounding the structure.

Actually with different radiation boundary distnace from the structure I was getting different value of characteristic impedance from the TDR plot. So was curious what should be the distance of radiation boundary from the structure.

Please find the screenshort for your reference and help me with distance of radiation boundary from the structure. 

My structure if simulation is twin rod in HFSS 3D and it is surrounded by the dielectric. 


Hope this make my question more clear. Thanks