Electromagnetic Wave and Photons? An EM wave consists of photons. How are they generated?
It’s my understanding that a radio transceiver creates an oscillating voltage on a conductor matched with a ground; this device being an antenna. Do charged electrons move back and forth at high energy from the conductor to ground? In this process perhaps collide with each other, moving an electron to a higher energy orbital state, then lower state which causes a photon emission at some angle?
 A: Classical picture
Classical description of electromagnetic waves emission is based on Maxwell equations, which predict that accelerating charges (or, in other words, a current that is changing in time) will emit electromagnetic waves.
Thus, radio emitter consists of a generator that creates current oscillations of a desired frequency, and an antenna, which efficiently couples these oscillations to the transmission channel (which is often just the outside space, but which could be also a metallic wave-guide or an optical fiber).
Quantum picture
Quantum description of the emisison is best udnerstood on the example of lasers, where the electrons jump from higher energy levels to lower energy levels and emit the radiation with frequency determined by the energy level spacing:$$\hbar\omega=E_2-E_1.$$(See the figure in the linked article.)
Why the two seem different
While the emission of radiation by oscillating electrons in a radio transmitter can be explained in quantum terms, one should not confound the two pictures:

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*In the case of a laser (or, in general, the radiation emission by atoms) we are talking about discrete energy levels.

*In case of a radio transmitter we are talking about a metallic antenna, where electrons are free to move, so there are no descrete energies. The emission is due to electrons acceleration and desceleration, which in quantum terms can be explained as Bremstrahlung - emisison of a continuous spectrum of photons (i.e., photons of many frequencies), which become a well-defined frequency as a result of constructive interference.

A: A radio wave is a special form of EM radiation.
In a thermal source, excited electrons "collide with each other, causing an electron to go to a higher energy state and then to a lower energy state, causing photon emission." That's right.
The same thing happens in the antenna rod. The differences with a thermal source are

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*the electrons are accelerated synchronously in the same direction, which produces polarized radiation

*the oscillating intensity of the emitted photons depends on the power of the wave generator and the matching of the intended frequency with the length of the antenna rod

*each individual photon moves only a bit along the rod (see drift velocity) and collides many times with other electrons.

The consequence of your question is that a radio wave is an oscillating stream of photons with very different frequencies.
