radio waves

Discussion in 'Wireless & RF Design' started by bhuvanesh, Jun 19, 2014.

  1. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
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    while watching video i have seen this statement "oscillating electric field oscillating magnetic field not electromagnetic wave"i dont understand what he really mean.thank you
     
  2. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    What video?
     
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  3. dougc314

    Member

    Dec 20, 2013
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    Without getting too mathematical, which I'm not really able to do any how I can say that an "electromagnetic wave" such as a radio signal has two varying fields, an electric field and a magnetic field. They are vectors and their direction vectors are at right angles to each other, and as they are two vectors, form a plane. The direction that the radio wave propagates is out of the plane. The Wikipedia article http://en.wikipedia.org/wiki/Maxwell's_equations on Maxwells equations has a very good animated graphic of the E fields and I fields of an electromagnetic wave.
     
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  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    and maxwell also says that you cnat have a varying electric field without a magnetic field, or a varying magnetic field without an electric wave at 90 degrees to it.
    one creates the other and both toogether are an electromagnetic wave.
     
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  5. nsaspook

    AAC Fanatic!

    Aug 27, 2009
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    I think it better to say they simultaneously exist as the properties of a single entity and propagate together as real energy moves across space. Create implies one is caused by the other by a process that requires time (lack or presence of causality), so whenever the magnetic field is changing, so is the electric field, and vice versa is 'closer' to being correct.

    https://www.youtube.com/watch?v=VdoL8IOwJw0
     
    Last edited: Jun 19, 2014
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