What could be causing this 40 GHz signal to look like two overlapping waveforms on a 63 Ghz real time oscilloscope? On the scope I see the signal out of a 40 GHz signal generator outputting a CW sine wave as:
It looks like it actually is wiggling with 4 different hi and low voltages. When turned down to 35 GHz, it doesn't show the behavior:
I just want to sanity check that this isn't due to a scope setting, the sampling is at 160Gsps [Edit: I previously incorrectly said 80 Gsps] and I varied the memory depth from Kbps to Mbps. Does it look like it is some second harmonic causing this? Is it more likely due to the signal generator (a VNA outputting CW) itself, or bad connectors in the cabling giving bad VSWR?
Thanks for tips and hints!