Roy Lewallen, W7EL wrote:
"Even identical array elements "don`t" necessarily extract the same
amount of energy. The reason is again mutual coupling."

Yes, and driven elements have a load. Parasitics do not.

In a parasitic array, the field strength at a distant point is a
function of the currents in both elements when it consists of two
dipoles.

It is true "the parasitic element extracts no power from an impinging
wave". It has no load to accept the power. It is a short-corcuit rod or
wire. It has current induced from a passing wave of acceptable direction
and frequency whether its source is from a driven element or from a far
away transmitter.

The excitation of a parasitic element, if no heat is produced in the
slemsnt. is 100% re-radiated. The element has a resistance which
consists of its self resistance and its mutual resistances. The total
composes the radiation resistance of the element which is the source
resistance for the radiation from the element.

My original comment was in support of Arnold B. Bailey who said
something about increasing antenna gain by 3 dB every time you double
its size. Precisely, that`s not true, but I gave an example from Kraus
where he did much the same thing.

Best regards, Richard Harrison, KB5WZI