Funny..
I have been reading about this subject as well, last days.
A dipole antenna works, because the current in both parts, are running in the same direction. Otherwise they would cancel eachothers fields.
The half wave creates at in the middle, on the most outside part of its wave, HIGH VOLTAGE
Now, what to do with the 2 electrodes of Stan?
As you said, it looks like a coax cable.
So, fields that cancels eachother out.
Thats not what we want.
And thats not what it is....
What you see here are 2 antenna,s.
One that transmits a positive wave annex voltage field and at the same time the other one transmits a negative wave.
Chokes are the transmitters.
Basically, one choke does a halfwave and the othe choke the other part of the full wave.
To keep the polaritation in place, the diode is there...
Have a nice weekend!