The programs vertload.exe and loadcoil.exe produce similar results for radiation
efficiency and radiation resistance. In both cases the antenna is configured as
a 6 meter vertical with a 10 cm long, 75 mm diameter coil in the middle.

However the coil dimensions or the input impedance do not match between the
programs. Vertload predicts a 50 turn coil with an ATU capacitor of 1289 pf.
While loadcoil predicts a 31 turn coil and 0 feedpoint reactance.

What causes the difference? Which one is the better model?

Thanks - Dan kb0qil