Putting together some quick models, here is the radials and bottom dipole element all attached compared to a standard 1/4 ground plane at the same height.
The results aren't even comparable, so it is definitely not wired as it appears at first glance... So to continue I need more information.
Edit, added the below section.
New model, that antenna in freespace.
This explains why its gain in he above comparison is so low, its dumping most of its output into the earth below... This actually raises more questions for me.
The antenna elements, are they all the same length? Are either of the vertical elements longer (or shorter) than the rest? I ask this because I am wondering if it is possible to steer the lobes in this design to get a more favorable output?
Also, are we sure the top element is the driven element? Perhaps the lower element is, or maybe even one of the what we would call the ground plane elements?
So many questions...
Unfortunately I don't have to much more time to play with this today, gotta go to work...
The DB