Richard Fry 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."

I`m not agreeing or disagreeing, just listing facts.

Arnold B. Bailey in "TV and Other Receiving Antennas"on p. 500 gives the
gain of a horizontal half wave wire (thin), center-fed as zero dB at its
center frequency. He should. It is his reference for all other antennas.
His authority is the famous G.H. Brown in Proc. I.R.E., Vol. 33, p. 257,
April 1945. Antenna resistance = 60 ohms.

On page 538, Bailey gives the free-apsce gain of the quarter-wave
vertical antenna. It too has a gain of zero dB = 0 dBd. His authority is
A.S. Meier & W.P. Summers in Proc. I.R.E., Vol. 37, p. 609, June 1949.
Antenna resistance 28 ohms.

Power is current squared times the resistance..

Terman says on page 886 of his 1955 edition:
"Effect of Ground on Directive Gain of Ungrounded Antennas. Consider an
antenna is far enough from ground so that the total power radiated by a
given set of antenna currents is independent of the presence or absence
of the ground. Then a ground reflection that reinforces the main lobe
will double the field strength of the main lobe, and so will increase
the directive gain of the antenna system by a factor of 4." (thet`s a
power ratio of 4)

On page 885 Terman says:
" Consequentially (due to ground reflection nulls), to obtain strong
radiation in the directions approaching the horizontal using a
horizontally polarized radiating system, it is necessary that the height
of the antenna above the earth be of the order of one wavelength or
more."

Also on page 885 Terman says:
"In the case of horizontal polarization the effect of imperfect ground
is seen to be quite small, especially at low vertical angles. With
vertical polarization the ground imperfections have greater effect; in
particular, the filling of the nulls at moderately low vertical angles
is very pronounced."

For the power to be the same in a vertical mast and a wire dipole, the I
squared R must be the same in both cases.

Best regards, Richard Harrison, KB5WZI