Roy, W7EL wrote:
"The principles involved are really simple and I hate to see them made
unecessarily complex by misinterpretation."

Amen.

Directive gain according to Terman is distribution in space of radiated
power versus the power that would be radiated by an isotropic. Losses
are not considered.

Power gain takes loss into account and is the ratio of the power
necessary to an isotropic versus the power to a gain antenna required
for the same signal strength in the same direction.

Kraus says the directive gain is the ratio of maximum power density to
its average value over a sphere as observed in the far field.

Terman and Kraus agree in their calculated examples. The directive gain
of an elementary dipole (Kraus says maybe i/10-wavelength) is 1.5. It
can be found on page 34 of Kraus` 3rd edition. It`s the same on page 871
of Terman`s 1955 edition.

The directive gain of a 1/2-wavelength dipole is 1.64 for Terman. For
Kraus, it`s 1.63 on page 35. These are power ratios, not dB.

Best regards, Richard Harrison, KB5WZI