...It can't come from ground losses because we can't change the ground losses...
Perhaps you can't change the ground loss, as measured in ohms. But you CAN change the
amount of power dissipated in the ground loss, and therefore the dB impact it has on your
Say your ground loss is 10 ohms. If your antenna has a radiation resistance of 0.1 ohm and
ignoring all other losses, you'd have an efficiency of about 1%. If you redesign your antenna
to have a radiation resistance of 1 ohm, then you can raise your efficiency to 9%. You've
improved your signal 8dB without changing the ground loss.
One way to increase the radiation resistance is to move the loading coil up higher on the
whip. A base-loaded antenna (which would be the case using a tuner at the base of a whip)
is about the worst case in this regard. Putting the loading coil higher on the antenna and
using a top hat can make a big difference.