In the picture below appears the geometry of the Hentenna.
No constructional details are given.

http://antennas.ee.duth.gr/recradioa...ntennaGeometry
/Hentenna%20Geometry.htm

However I can use a balun to connect the coaxial line with the connector.
Because of the skin effect there is current in the interior and the exterior
of the conductor.
Firstly this current is only superficial.A part of it ends into one of two
wires.
As result we connect an unbalanced system(coaxial line) with a balanced
one(conductor).
In order to avoid this we use a balun which is a geometry transformer.

I ask for more comments.

Emma