how to make 50 ohm transmission line
Hi, if you just want to see the performance of your 50 ohm transmission line (presumably, you have a jig with suitable connectors) with VNA, just do a full 2port calibration across your frequency band of interest. After calibration, you can see the insertion loss and return loss.
If you have done the design properly, you should get good return loss ( better than -15dB) at port 1 and port 2, that is, the line is well matched to the 50 charactersitic imped of VNA. If you display the VNA in smith complex chart format, you should see your S11, S22 plots centered at middle of the dsplay, at your frequency band.