Thank you for your reply. This is continutaion of previous thread you left unanswered.a
I switched to medium and low sweep speed – the same problem. Also varied number of points in the plot from 450 to 3150 – same problem. Tried different calibration – User Cal an Sys Cal – same problem. I believe noise/spikes I see is related to heating of the unit. When I turn it on from cold I get few minutes with no spikes. (Unfortunately this time is too short to do any useful work.)
Below attached plots of the same antenna in the same settings taken at different times: unit just turned on, after 7 min, after 40 min. You can see how initially there is no spikes, than a little bit and in 40 min it is pretty bad.
... see images in previous exchange you left unanswered.