Very nice.
You may want to post your system to the message group that is discussing test fixtures.
Part of the discussion raises the query on testing devices so full 2 port data is required.
I raised the TRL piece as I have used a combination of TRL and SOL or SOM on another vna.
David is correct that at lower frequency the cal is problematic. However, my fixtures lend themselves to TRL since there is no easy way to equip the DUT to coax.
So going forward with the nanovna will require a pair of decent bias tees or least ones that can be made part of the calibration process with minimum error and a switching system to turn the device end for end.
Thanks,
