Antenna & Earth=Potential Difference?

Discussion in 'Physics' started by ross, May 14, 2012.

  1. ross

    Thread Starter Member

    Jul 30, 2010
    46
    0
    If I put up a big antenna and drove a copper pipe deep into the ground, What kind of potential difference would I get? Would it be enough to be useful? If it is feasible at what scale? Ive always wondered about the physics of this.
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    This big say?

    http://en.wikipedia.org/wiki/KVLY-TV_mast

    The electric field strengths near powerful transmitter masts can get quite high - >100V/m or more within a few meters of the tower. The (near field) electric field strength reduces dramatically as the distance from the tower increases. Even with a very large receiving antenna carefully tuned to the transmitter frequency you would be unlikely to get a useful voltage source a few kilometers from the transmitter.

    I've heard a claim that some people have been known to steal RF energy using tuned circuits in their homes in close proximity to a radio transmitter. It's illegal to do so.
     
    Last edited: May 14, 2012
  3. MrChips

    Moderator

    Oct 2, 2009
    12,415
    3,354
    We were pulling up a 14' sailboat (Albacore) on to the beach under some HV transmission towers. If you touched the mast or stays (guy wires) on the sailboat you got a shock!
     
  4. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    The earth and atmosphere also have a ( near DC ) field, can be many volts per meter, but at a high impedance so collecting energy is low until it is hit by lightening.
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,135
    1,786
    Think High Voltage e.g. several hundred volts at miniscule currents e.g. nanoamperes. The power output of an antenna is very small on the order of microwatts.
     
  6. ross

    Thread Starter Member

    Jul 30, 2010
    46
    0
    I don't understand do you have any references that I could look up?
     
  7. ross

    Thread Starter Member

    Jul 30, 2010
    46
    0
    Ah! so that's why we aren't plugged into towers,you couldn't have explained it better.Thankyou.
     
  8. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47

    just google: earths electric field
     
Loading...