> Is the output from that antenna a variable waveform photon, or is it multiple photons of different wavelengths being produced at once.

A photon is a fixed unit of energy whose energy is proportional to its color.

If the station is an AM station, the photon are pumped out as if the woofer were attached to a photon pump, pushing more photons out on the upwave, and pulling back to create a relative rarity of photons on the downwave. The audio modulates the amplitude of the output signal (# of photons). The carrier remains on one frequency, as tightly controlled as possible - "1410 on your radio dial" 1411 is a little staticky, 1415 is worse, and 1450 is a whole nother station. Carriers run from 680kHz to 1500 kHz.

If the station is an FM station, it still pumps out photons but the audio isn't encoded in the amplitude of the waves. Instead a signal is generated at say 95Mhz, but it's allowed to warble, to swing 0.1 Mhz either way. Music is encoded onto the warble, so that high notes are one wavelength and low notes are slightly different, a continuum that lets you trace out the audio waveform.

So the FM station pumps out a steady energy but the wavelength warbles between 95.0 and 95.1, so that a curve y=f-95.0 plots the musical waveform. It's a little more ocmplex bc they actually create two signals on either side of 95.0, 94.9 for left and 95.1 for right. Or VV.

If I haven't totally munged this explanation, perhaps someone can explain how volume is encoded in FM.