Hi Jim
MFJ company says that MFJ259 antenna analyser becomes inaccurate when measuring reactances below 7 Ohm or above 650 Ohm, i am really impressed with the good S21 responses you have even with a high value Z Renormalisation as 440 , Congratulations, may be NanoVna-H4 has a little more dynamic range then MFJ instrument what can explaine this even if we loss 10 times the accuracy when we are away from 50 Ohm , but in this case we should pay some attention to the thermal stability of the NanoVNA , give it some time to startup before calibration and measurements, anyway i am happy with this Z-renomalisation functions.
73s Nizar
