Oh, OK. That would mean your explanation is better than his.:smileWell Rabbit.
He had no explanation as to how he went about figuring what he did.
The model he is basing it on is a single solid element
The Archer is 2 separate driven elements being combined together using dissimilar materials.
The guy types like 91xg without the rambling.

The first image shows a Gamma Match. It is a way to match a dipole to a coax line, but there is no balun. The position of the tap is adjusted to match the impedance of the feedline. The capacitor cancels out the reactance of the gamma rod.

In photo 2 I see a 3/4 wave folded dipole connected to a coax line. The folded dipole is a balanced element; the coax is an unbalanced line. I see no Gamma Match or balun. Usually, a 300 balanced line or a 4:1 balun is connected to the DE.

Is photo 3 his antenna?
That's not a Gamma Match. I can't tell what's on top. It looks like the DE is a rod dipole split in the center. The coax, which is an unbalanced line, is connected to a dipole, which is a balanced element. I see no Gamma Match or balun.
And, what is that extra wire?
Just because the gentleman got it to work, doesn't mean it's the best way to do it.
Gain tests and SWR measurements would be needed to document any improvement.
I'm not impressed with his design.