Antenna selection

Discussion in 'The Projects Forum' started by metal_militia7, May 12, 2011.

  1. metal_militia7

    Thread Starter New Member

    Jun 13, 2010
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    Hello Everyone,
    There is a cell phone tower near my house I am wondering what kind of antenna should i use for the reception.

    I also want to observe power received using Spectrum analyzer.
    please help me out with this thing.


    It is for my own research. I am thinking of doing some research on cell phone towers electromagnetic radiation and power.

    So far i have gathered the information that cell phone towers are 200ft tall. And transmits power ~ 25W. And freq of 850-900 and 1850-1900 MHZ

    I am curious how much power can i grab out of 25 W.
    Thank you
    Metal_militia7
    *****There are ideas around you, you just need eyes to see them.*****
     
  2. OokamiNora

    New Member

    May 12, 2011
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    well, i dont know how much power that one has, but i know that there are some towers (like the one at my previous house) that you can set up antennas on a metal sheet and use a few other components, and make eggs in the morning... i dought you can run your house off it, but i bet theres a way to make something like 1 side of a transformer and collect the energy in capasitors and then send it on, but i'm new to circuitry, so you would have to look around at how to chanel that energy.

    I hope you can find a way!
     
  3. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Search "cell phone yagi" for directional cellular antennas. These are marketed primarily to increase the range of cell phones that have an auxilliary antenna connector but because of their directionality, they will allow you to effectively limit your reception to a particular tower.
     
  4. metal_militia7

    Thread Starter New Member

    Jun 13, 2010
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    Than you,
    But what gain should I be looking for Yagi.

    these antennas seem little expensive, do you know any place where they can be bought @ reasonable price?
    metal_militia7
     
  5. beenthere

    Retired Moderator

    Apr 20, 2004
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    Depending on the interpretation of that statement, you are going to attempt to obtain useful power for free. Perhaps the cost of the antenna will be covered by the power you are able to take.

    Yagi gains are determined by the accuracy and spacing of the elements, plus the number of drivers and reflectors.
     
  6. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  7. KJ6EAD

    Senior Member

    Apr 30, 2011
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    I think the lowest price I've seen for a cell yagi was ≈$42.00. Gain probably won't matter much for your purpose. Higher gain would mean higher price, a longer antenna with more elements and would result in a narrower receive pattern. Manufacturer's claims of gain figures should be taken with a large grain of rock salt.
     
  8. metal_militia7

    Thread Starter New Member

    Jun 13, 2010
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    I want to see at least 10dB power received in the Spectrum Analyzer. Has anyone tested Yagi to receive this power? I want receive free power, and use it .
     
  9. beenthere

    Retired Moderator

    Apr 20, 2004
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  10. CDRIVE

    Senior Member

    Jul 1, 2008
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    Pardon my skepticism but do you have any verifiable proof of that?
     
  11. CDRIVE

    Senior Member

    Jul 1, 2008
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    Excuse me but I'm laughing hysterically! If there was that much RF energy floating around us we would all be sterile! :rolleyes:

    EDIT: By the way... dB is a relative measurement system. It can be converted to Watts only when referenced as dBm. 0dBm=1mW dissipated by a 50Ω load.
     
    Last edited: May 14, 2011
  12. metal_militia7

    Thread Starter New Member

    Jun 13, 2010
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    pardon me,I meant dBm.
    :mad:
    I believe RF harvesting is certainly possible.
     
  13. CDRIVE

    Senior Member

    Jul 1, 2008
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    Uh...yeah! I plan to power my central air doing that.:rolleyes:
     
    metal_militia7 likes this.
  14. KJ6EAD

    Senior Member

    Apr 30, 2011
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    RF harvesting is possible but it rarely provides enough energy to overcome it's own system losses, much less pay for it's construction or perform useful work. The only practical use that comes to mind is in passive RFID tags.
     
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