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Electromagnetic waves and attenuation

  1. Feb 23, 2006 #1
    Hi i am trying to understand how long a electromagnetic wave can travel.... What is the attenuation that the electromagnetic wave face in the atmosphere... This question arised when i have read that marconni at the beginning of 20th century has sent electromagnetic waves from england to canadA!!!! How long the electromagnetic wave can travel in a free space model?
     
  2. jcsd
  3. Feb 23, 2006 #2

    jtbell

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    Staff: Mentor

    This is really in the domain of classical electrodynamics, not quantum physics, by the way.

    Propagation of radio and television signals is a very practical subject and has been extensively studied. Try a Google search on "radio signal propagation" and "television signal propagation" and you'll get many useful links.

    I've gotten interested in this subject myself recently, because I'm one of those old-fashioned people who gets TV "over the air" from terrestrial broadcasters, rather from cable or satellite, and I've recently switched from analog TV to digital TV. I'm in a "deep fringe" area where most TV transmitters are over 50 miles (80 km) away. I want to improve my digital TV reception, so I'm starting to study signal propagation, antenna design, etc.
     
  4. Feb 23, 2006 #3
    Thx a lot but i think if i search in google about signal atenuation i will get a headache with all these info ... Can u plz suggest me sth else?
     
  5. Feb 23, 2006 #4

    jtbell

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    Well, I'm just starting to look so I haven't found anything comprehensive yet. I did find this just now, though: a BBC TV broadcast from London in 1938 that was carried to New York by freak atmospheric conditions and filmed off a TV screen by engineers at RCA laboratories!

    http://www.apts.org.uk/recording.htm
     
  6. Mar 1, 2006 #5

    Meir Achuz

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    Short wave radio waves bounce off the ionosphere, which greatly increases their range. This is more effective at night, which is noticeable even for long radio waves.
     
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