Sort of similar to the one of the 6m
omni. Instead of using twin-lead, this design makes use of a more or
less regular double bazooka antenna (coaxial dipole). Your attention
shall be drawn to the available standart literature, such as Rothammel.
In order to "compute" the dimension, Karl Rothammel mentioned that the
total length of the dipole shall be 95% of the free-space wavelength.
The short-circuit bridges (closing the folded dipole) are to be placed
at a distance-fraction being equal to the velocity factor of the coax
cable used, which will be 66% using RG-58 or RG174.
Some Simulations....
No sofisticated simulations have been done on this aerial... Just to
give a short impression what can be expected, a very rough simulation
using "real" ground setting with an antenna height of 9.5m (corresponds
to a height gained by a
DK9SQ
"fibreglass telescope tower").

the horizontal directional diagramm

and for completeness, the vertical diagram too