Thanks for explain the diagram.
But now i have another doubt.
i have found on cebik home page an example of w8jk antenna.

You can seee at http://www.cebik.com/fdim/fdim9.pdf on page 6 and 7

in this project the full element is 44'(13.2m) but spacing is 22'
(6.6m)
So in this case the element is longher than 1/2wl ( i'm also reading
that the optimum is that the full element is from 1wl to 1.25wl, so
from 20m to 25m) and spacing is between 1/8 wl to 1/2wl.

What is the best choise?
If element is to short i may have very low impedence