The 85054B is designed for use to 18 GHz and so I assume the coefficients are optimized to cover that full 18 GHz frequency span. Although I have a 20 GHz VNA, I also have a 3 GHz one (8753ES), and suspect that there would be more suitable parameters for use to 3 GHz. Has anyone derived them, and can share them? I also regularly use the 85054B to 6 GHz on my 8720D, and rarely above 6 GHz.
A related question. Can anyone share a Keysight calibration certificate for an 85054B or 85054D? I suspect that has the modeled phase, and on the off chance there are sufficient frequency points, I could fit my own polynomial to the phase listed on the cal certificate as the Keysight model.