Why do electromagnetic waves detach from the antenna? In most explanations of how antennas work they say that because of kinks in the electric field of an antenna meets at one point and detaches... I looked up reasons for why this happens but all I got was an answer saying that electromagnetic waves travel in the direction of the Poynting vector.
So I have 2 questions:

*

*Why does the electric field detach from the antenna and propagate?


*Can that be explained by the Poynting vector?
 A: The build up of Maxwell's equations was long, and the experimental confirmation that light is the electromagnetic waves predicted by them took a while. There  are "laws", relations which were defined from experimental observations,  which are as an axiomatic underlayer so that the equations appear consistent and give the electromagnetic wave as part of its solutions, which eventually fitted light observations at the time. It also explains mathematically the classical electromagnetic wave from an antenna.
In classical electrodynamics , a changing current generates electromagnetic waves. A moving charge with a constant velocity is a current of charge.An accelerated charged  particle is a changing current and thus has to give off electromagnetic waves according to the equations. That is how antennas work, by changing currents. At the time the current carriers were a hypothesis.
We now know that they are electrons and positive ions, depending on the set up. At the quantum mechanical level, a change in velocity for an electron means an interaction with the field , either giving up energy or radiating energy away and there are QM precise calculations on the probability of an accelerated electron to radiate a photon. There is continuity in the theories of physics and it can be shown mathematically that a confluence of photons builds up the classical electromagnetic wave of Maxwell equations.
A: The "electric field detachs" from the antenna because it is not simple electrostatic field, but instead it is transverse wave generated by accelerated electrons in the antenna. Accelerated charged particles create such propagating waves of electric field.
Poynting vector is a measure of EM energy flow, by itself it does not explain how electric field behaves. Maxwell's equations (and boundary conditions) explain that.
