I believe I tried lengths of a 3% to 5% shorter length with the
director, than the drive element (i.e., the one in front of the
reflector), settling on a 4% shorter length ...

So about 26.8mm square?

With a spacing between driven element and director of ~0.2
wavelength, center-to-center.

So the director should be 25 mm forward (toward the uwave source) of the
driven element? (3e8 / 2.4e9) x 0.2 = ~25mm

Do these numbers look right?

Thanks.