How did you connect VNA to antenna?.
I understand you are connecting VNA to 1:7 (49 is squared 7) low impedance side transformer, which is not ideal, so modifies the antenna impedance. Is there a piece of coax to connect VNA-transformer? If yes, did you compensate cable length any way? Have the antenna a counter poise 0,05L? If does not, then the feeder is part of your antenna and it modifies impedance too.
If you load transformer antenna side with 2400R, the VNA will show an impedance curve, smith graph, close to 50R but complex values too. See attached picture.
Juan Pablo EA4CIV
