Where is the positive and negative on an antenna?
I think you might be getting confused between monopoles and dipoles: -



Look at the left picture above - it is called a dipole and it requires a balanced two wire connection. It produces and receives radio waves but, along the horizontal centre line the electric and magnetic fields are neutral and you could insert a thin horizontal conducting sheet in that plane and the operation of the dipole would be unaffected.

You can even short that conducting sheet to ground and it would still be unaffected. So then we come to the monopole (on the right). It has taken what I have said and drives just one half of the dipole arrangement with respect to earth. Do you see the difference?

A monopole requires one wire connection to the antenna and one wire to ground. The wire to ground can be very tenuous (as per a transistor radio tuned to FM) and that connection relies on the radio's 0 volt capacitance to ground to form that connection. Sounds unfeasible but it's true - do some math on what capacitance is needed and you'll figure it's true.