I am having issue with full 2 port cal with unknown thru on ENA E5071C.
I am getting periodic ripple across wide band in Return Loss measurement.
That only happen if I use mechanical cal kit in Unknow Thru, however I do not see that in Thru/delay.
If I use Ecal (I see that now it have Unknown ON/OFF function), with Unknown OFF the return loss is smove, with Unknow ON it also show some ripple (smaller than from mechanical calkit).
I use latest firmware 11.34. I also downgrade the firmware to 11.02, similar behavior.
I first suspect the the VNA have some issue, however single port calibrations show smooth return loss.
For Unknown Thru I set adapter delay to 81ps (measure with port extension on PNA-X).
For whatever reason if I set that delay to Zero ps it look like there is not much effect on the calibration.
The cal kit that I used is 85052D ( just come from annual calibration) the Ecal N4433A.
Somebody need to look in that.