Producing visible light from a radio wave transmitter: why is it not possible? If it is, what are the limitations?
Radio antennas generate electromagnetic fields. Light is a physical particle of energy called a photon. Since the the radio antenna doesn't generate particles of energy, no matter the frequency, it can't produce light. The flow of current in a conductor generates an electromagnetic field that propagates from the conductor. The generating of photons from an electric current is a different process and is on the atomic level. The electric current releases energy (photons) from individual atoms. Probably the most commonly know application of this process is the light emitting diode (LED). Until the scientific community admits that light, in fact, isn't part of the electromagnetic frequency spectrum, since light has no electric or magnetic properties, these confusions will continue.