@eevblog The graph at the first seconds is wrong.
If the three capacitors are the same size then all the three have the same series inductance so the graph of impedance at frequency higher than the highest resonant frequency should merge to one line.
@K3TripleR The rest of the coax should be just a transmission line that feeds the power, not contributing to the radiation and is not a counterpoise or part of the antenna.
@K3TripleR You don't understand how a hwef dipole works.
It is a dipole which its feeding point is about 5% from one end.
The 5% of the short side of the dipole is implemented by the shield of the feeding coax by adding a common mode choke on the coax at 5% wave length from the feed point.