You keep asking the same question, so maybe one has to start at the beginning.
Bremsstrahlung produced by a high-energy electron deflected in the electric field of an atomic nucleus
The electric field of the nucleus is very strong, and the deflection of the electron generates a photon which flies off with velocity c, and the electron departs with smaller energy. If it meets another nucleus , it will degrade in energy by emitting another photon again. The fields of the atoms are very strong, and the photons leaving the interaction are of X ray frequencies.
The whole process can be calculated quantum mechanically giving the probabilities of such radiation happening.
This is a general phenomenon for all electron energies: If the electron is decelerated by entering some electric field region, it will emit the photon, if it is accelerated the same will happen, a process that is also in the equations of classical electromagnetic theory, except there the mathematics gives an electromagnetic wave, where the energy leaving has a sinusoidal form.
An antenna is a geometrical shape that uses conductors. Conductors have a conduction band, where the electrons are practically free of the atoms and can be moved , accelerated and decelerated with applied electric fields. The energies used are very much lower than in in the production of X-rays, but the logic is the same: acceleration and deceleration of electrons forces photons to be emitted.
This is done by the current carrying circuits in the antenna circuit. At the electron level the acceleration and deceleration imposed with the period of the current of the circuit, forces individual electrons to emit a photon at an angle to the field, depending their motion and the momenta involved.
There are order of 10^23 electrons dancing in tune in the antenna, and thus an enormous number of photons in synchrony are generated leaving immediately (BUT continuously) in synchrony with the signal imposed by the currents of the circuits.
The superposition of all these photons creates the electromagnetic wave, in this example the radio wave, building up the electric field of the classical wavewave ( the magnetic is perpendicular to the electric). Each photon leaves with velocity c, but there are so many that the classical wave appears continuous.
Here is a graph as an example of how photons add up to the classical wave that may help.
The electric field of the electromagnetic wave is the red arrow, the magnetic will be perpendicular to it and the direction axis.