Roy Lewallen wrote:

Correction. Even identical array elements *don't* necessarily extract
the same amount of energy. The reason again is mutual coupling. In a
four-square receiving array with very low ground loss, one of the
elements will actually radiate power. This power comes from power
extracted from the wave by the other three. In a Yagi array, the
parasitic elements extract no power at all from an impinging wave; only
the driven element does.

Roy Lewallen, W7EL

Another example that can be divorced from ground effects and easily
modeled in free space is a 4 by 4 array of yagis - an EME array. The
corners are one set, the outside horizontal pairs are another, the
outside vertical pairs are another, and the inside 4 are another.

I have a simple 4 by 4 by 3 element AO array as an example if anyone
would like a copy.

tom
K0TAR