What did you use for your frequency sweep in the TDR Wizard setup in SIwave? I think the default sweep setup only goes up to 5GHz. Just looking at the waveform it looks like that rining is ~6GHz or so. Given that the TDR source in the Circuit tool uses a 35ps rising edge by default, we have to be careful with out of band energy unless you have upped the bandwith in the TDR setup. Alternately, you can go into the Circuit setup and slow down the edge of the TDR source to see if that changes anything.
You are navigating away from the AIS Discovery experience