Also, if the cal is done offline in software, then changing coefficients (i.e. recalibrating using a different set of coefficents) is purely software and doesn't require another sweep. So it would be technically possible to do a full sweep and change cal definitions on the fly. The definitions would match the real cal standards very closely.
If you have a VNA where you can access to the calibration coefficients, like the 8753 and, I think, most of the ones not targeted at hobbyists, you can simply use something like scikit-rf to do the calibration using the calkit S parameters directly (no need of building any model of them) and then write the computed calibration coefficients back to the VNA. I don't know if this is what the METAS VNA Tools can actually do or if it allows only a post processing of raw data acquired from the VNA.
Then another issue is the calkit repeatability, with cheap stuff you never know how it will behave tomorrow ![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Yes, very true. In this way we can remove the model entirely.
With the cal kit repeatability issue, I think that is where buying high quality open/shorts and characterising them should produce a better result than DIY.
Also, the proposal I mentioned a while back, was to not use an open standard at all when the VNA has a female SMA port.
As long as it is characterised then is there any point in connecting a standard to it, aside from a slight noise reduction? This is one less connection to make when calibrating.
I need an s1p file from a calibrated VNA which has a female SMA port left open. Since we have optimisation software, I will try to create a model for it.