Atomic resonance from EMR

toneboy1

Hi, I have been researching antennas all day but I can't figure out how specifically they work in that; they seem to oscillate AC through like a band-pass filter (LC circuit) to get a signal. I'm assuming there is some sort of current 'sloshing' in and out of the antenna as they do. Also that they are most efficient at some fraction if not the full wavelength of the desired signal.
BUT what I can't figure out is you've got an AM radio that can pick up, say, 40 frequencies (stations) and the same aerial could be used for FM just as well (much smaller frequencies).
SO the electrons on the surface must be resonating with the full spectrum of AM and FM, how could you still get any ONE signal tuned in with the circuit with those electrons jostling about from an infinite amount of frequencies? Sounds like a mess.
Also, if anyone is inclined I was wondering if two EM waves of the same freq could add via superposition on the same electron to become ionizing (if each wave was say just below UV), or what's the case there? E = hf would indicate no, but I don't see where the energy would go (thinking of mechanical waves).
THANKS! (this is my first time)