I wrote:
"With a perfect ground in this situation (MW vertical tower) the base
current in the vertical mast is twice what it would be for the same
power applied to an equivalent wire dipole (less a ground system) in
free space -- resulting in 3 dB system gain."
to which Richard Harrison responded.
____________

Excuse my inaccurate statement about that current, and thanks for catching
it.

The input resistance of a 1/4-wave monopole working against a perfect ground
plane is 36.5 ohms,* or half that of a 1/2-wave dipole in free space. A
given input power then results in 1.414X more current in the monopole than
the dipole. Hence the monopole radiates 1.414X the field of the dipole.
And, as shown in Kraus 3rd edition, Table 6-2, a 1/4-wave monopole against a
perfect ground has 3 dB more gain than a 1/2-wave dipole in free space.

Increasing the field from the 1/2-wave, free space dipole by 1.414X in the
above example would require doubling its input power (3dB), which would
result in the same 1.414X increase in its current -- to the same value as
seen in the monopole with 1/2 that power.

* per Kraus 3rd Edition, p 567

RF