The polarity of an antenna refers to the orientation of the (oscillating) electric field. A vertical antenna radiates the electric field in the vertical orientation.
The magnetic field is in "time-phase but space-quadrature" to the electric field, that is to say its strength mirrors that of the electric field with respect to time, but it propagates through space at ninety degrees to the orientation of the electric field. (quadrature in space).
Introducing the magnetic field in a discussion where the electric-field is the phenomenon of interest is in my view obtuse and designed to be deliberately misleading. Most radio equipment operates by receiving the electric-field. (However, some satellite-dish LNBs use the magnetic-field for better resistance to electromagnetic pulse damage.)