Dave wrote:
. . .
The practical application deals with the efficiency of the antenna. Is
that tuned 15 degree long antenna a 12.5 ampere degree antenna; or, is
it a 10.218 ampere degree antenna? [That's approximately a difference of
1 dB in antenna performance.]
. . .

I believe you're comparing the field strengths from two antennas both
driven by the same current. If you drive them with the same power, a
more fair comparison, you'll find a negligible difference in field
strength. Efficiency is another issue, solely related to losses in the
antennas. Without knowing what those losses might be, we can't say
anything about the relative efficiency. In practice it'll probably be
extremely closely the same also.

Roy Lewallen, W7EL