Here's another issue revealed by trace dots. The data is for a Johanson 390 nH inductor. Note the trace gap at about 7 o'clock. The frequency steps are uniformly 1 MHz so the gap is not due to a frequency jump. Something changed dramatically in the VNA as the frequency crossed 7500 MHz. I wonder which side of the gap is correct. Or is either? If the application was important, I would trust any part of this data.
I had looked at this file several times with a normal trace, as shown in the second image, and I never noticed the flat spot that shows up as a gap with dots.
Brian
