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Is RF transmitting electrons over the air?

Discussion in 'Radio and Wireless' started by NuLED, Jun 21, 2013.

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  1. NuLED

    NuLED

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    Jan 7, 2012
    Hey guys - so, back to those basic gaps I have about EM.

    With RF, how is the energy being transmitted over the air? I can understand the holes/electrons concept in the wires, but when it gets to RF frequency, what is actually being transmitted, to then induce current (or voltage?) in another conductor?

    Would it be correct to envision the electrons inside a wire, when "agitated" to RF frequency, suddenly radiate off as disembodied wave-like energy (not unlike duality of photons?) that then induces current (voltage?) in a receiving conductor, and in the conductor then "become" electrons again and travels in the current?

    I have a hard time envisioning the conduction channel over-the-air / space. Although I suppose one can say the same thing about photons traveling through space like any other particle.
     
  2. duke37

    duke37

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    Jan 9, 2011
    Leds emit photons, the eye is most sensitive to green which is about 500nm wavelength.
    Radio waves are no different other than the wavelength (frequency).

    The energy is transmitted as a electrostatic and magnetic wave.

    I cannot help with the physics but there will be no electron movement in space as there are no or very few atoms.
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    No. electromagnetic waves are not electrons moving through space.
    Electromagnetic waves are a combination of alternating magnetic waves and electric waves. This is "pure energy" moving through space.
    An antenna can catch this energy and the incident electromagneti waves will force the electrons in the antenna wire to move at the waves' frequency. But these electrons have been in the antenna wire before, they do not come through space.

    Similarly, a photocell will react to electromagnetic waves of the right frequency (i.e.light) by separating electrons and holes with the photocell's material, thus craeting a potental diference (voltage) across the photocell's pins. Here, to, the charge carriers have been there before, the electromagnetc energy only helps to separate them.

    Compare this to waves on an ocean shore: They transfer huge amounts of energy but the water does not move in the direction of the energy transfer (towards the shore), instead it moves up and down, the energy is within the movement. (I know, this is acrude comparison and physically not correct).
     
  4. NuLED

    NuLED

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    Jan 7, 2012
    OK thanks, starting to make sense.

    So, WHAT is the electromagnetic wave itself? Or are we getting into the realm where the energy transmission is actually happening because the space/time fabric is being "agitated" (analogous to the ocean wave example)?
     
  5. Laplace

    Laplace

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    Apr 4, 2010
    The movement of electrons in the antenna generates corresponding vibrating electric and magnetic fields which manifest themselves as transmitted photons which then create vibrating electric and magnetic fields at the receiving antenna that generates the movement of electrons. Yes, as you mentioned, it is wave-particle duality. But how much of quantum electrodynamics must one understand in order to design a radio circuit? I like to recall the words of the physicist Richard Feynman from his lecture on this topic:

    "On the other hand, I think I can safely say that nobody understands quantum mechanics. ... I am going to tell you what nature behaves like. If you will simply admit that maybe she does behave like this, you will find her a delightful, entrancing thing. Do not keep saying to yourself, if you can possibly avoid it, 'But how can it be like that?' because you will get 'down the drain', into a blind alley from which nobody has yet escaped. Nobody knows how it can be like that. So then, let me describe to you the behavior of electrons or of photons in their typical quantum mechanical way."
     
  6. NuLED

    NuLED

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    Jan 7, 2012
    Haha very good. Thanks. Although I never know when I reach a "limit" that it becomes non-pragmatic to go further. Indeed, sometimes it is tricky because you might skip over something that actually was important to understand. Such is the challenge of the newbie trying to grasp any topic.
     
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