I am using Nec Win Plus (NEC2) to view the SWR curve of my modeled
antenna. The actual antenna uses a 6:1 ratio balun. Is it incorrect
to just change the characteristic impedance of the line from 50 ohms to
300 ohms to see what effect a 6:1 balun would have on the SWR values? I
was just assuming that the line impedance was only really needed to
calcuate SWR - hopefully I am right.

Thanks,
Scott, WU2X