The three simple electric charge characteristics as it relates to an antenna specifically a dipole antenna are:
-
Charged particles have an electric field at all times
-
Charged particles create an magnetic field when moving at a constant speed.
-
Charged particles create an electromagnetic field when accelerating or reversing
Half wavelength antennas at resonance have characteristics of a capacitor in that the current leads the voltage by 90 degrees within the antenna. Standing waves of voltage and current occur and each form their own distinct half sine wave over the antenna whereby the current is maximum whenever the voltage is minimum. The ends are voltage loops and the center is the current loop.
When a reversing current interacts with a resonant antenna it allows part of the antenna's collapsing electric field lines of force to be isolated from the antenna and loop on themselves and be propelled away from the antenna by the antenna electric field since the fields repel each other. The newly isolated moving looped electric field lines of force create magnetic lines of force that are in phase and have the same sign of magnitude. In the electromagnetic field the electric and magnetic fields are combined and in phase but 90 degrees apart or perpendicular to each other in space.
The local antenna electric and magnetic fields are called near field which along with properly timed new incoming charges allow for this creation of electromagnetic radiation which becomes the far field. The voltage versus current 90 degree phase relationship in the antenna and new charge timing allow this far field radiation to occur.