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EM radiation

Discussion in 'Electronic Design' started by klyons, Jun 21, 2007.

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  1. klyons

    klyons Guest

    For an experiment, I want to be able to radiate a sample with
    electromagnetic radiation that I am able to vary in frequency over as
    wide a range as possible. I don't even know what a device that can do
    this is called- can someone please help point me in the right
    direction?

    -Kevin
     
  2. Phil Allison

    Phil Allison Guest

    ** Google TROLL Alert !


    ** Straight up.

    Just ask a really cool guy named Scotty to " beam " you.




    ...... Phil
     
  3. GregS

    GregS Guest

    The fields, either magnetic or electrostatic, will vary with the radiation device, such
    as antenna or coil. Antenna would need an RF power amp in the range you need.
    I used to have a generic power amplifier used to test ultrasonic up to about 10 Mhz.
    You feed the power amp with an RF signal generator. Low frequencies are best radiated
    with a coil.

    greg
     
  4. mpm

    mpm Guest

    You need an "RF Generator" or "Service Monitor".

    Here are a link I Googled using "IFR" to get you started, though this
    is not exhaustive by any means... (IFR is a manufacturer, and I've
    used them before with good results.)

    http://www.econ2way.com/service-monitors.htm

    This gear probably does more than you need, and they are expensive.
    You may be able to lease one. Or, you can try around two-way radio
    repair shops in your area and try making friends with one of the
    techs.??

    HP, and others, also make stand-alone RF Generators.
    You will need to know what frequency range you are interested in.
    You will also need to know how much RF power you wish to generate, and
    whether or not it exceeds the capabilities of the above.

    Then depending on what you intend to do, you may need to design a
    calibrated "antenna" system so you can control the RF transfer to your
    device under test. -mpm
     
  5. mpm

    mpm Guest

    I assume you meant radio-frequency.
    If otherwise, my post above may not be what you want?
     
  6. klyons

    klyons Guest

    That was very helpful- thanks a lot!
     
  7. Jamie

    Jamie Guest

    Hmm. A signal generator into a loop antenna? of course, you didn't
    specify how much radiated power you were looking for?
     
  8. Guest

    If you really want a wide RF range you might try a spark gap
    transmitter: http://en.wikipedia.org/wiki/Spark-gap_transmitter
    Of course you would probably interfere with every radio and TV
    for miles around.

    [8~{} Uncle Monster
     
  9. Chuck

    Chuck Guest

    And don't forget the sun as a source! At
    least IR to gamma.

    Chuck
     
  10. MooseFET

    MooseFET Guest

    Actually, the bottom end is much lower than that. It radiates a lot
    of 0.000125Hz
     
  11. mpm

    mpm Guest

    If my math is right, that's over 2 hours a cycle.
    So I guess you really can get sunburned with just a quarter-
    wave.... :)

    -mpm
     
  12. How does it manage that? An antenna even as big as the
    orbit of Earth is still small compared to that wavelength
    (of 2.4 billion kilometers). The Sun is positively tiny
    compared to that wavelength.
     
  13. Guest


    Carcinotron.
     
  14. whit3rd

    whit3rd Guest

    Electromagnetic radiation can be radio, microwave, infrared,
    visible light, ultraviolet, soft to hard X-rays, etc.

    The 'radio' range is about 200 kHz to 1 gHz - frequency difference
    10**9
    while the 'visible light ' range is about 10**18 hertz... so
    a pinhole and prism on a sunny day gives a pretty wide frequency
    variation.

    For 'as wide a range as possible' there are synchrotron sources of
    hard X-rays that can give 10**22 Hz frequency range.
     
  15. MooseFET

    MooseFET Guest


    As I understand it: The sun sends out streams of charged particles.
    This makes it appear much larger than its obvious size and there is a
    lot of horsepower available to drive the poor radiator.
     
  16. Tim Williams

    Tim Williams Guest

    Absolute frequency yes, but relative, no. Sunlight covers a little over one
    octave, if that (~400-1000nm). The sun puts out little IR (since its
    black-body peak is in the visible range), and the atmosphere filters the UV
    tail.

    Tim
     
  17. Jasen

    Jasen Guest

    a spinning magnet radiates

    Bye.
    Jasen
     
  18. Phil Hobbs

    Phil Hobbs Guest

    When you say "little IR", what are you comparing it with? Blackbody
    curves for different temperatures never cross--heating up an object
    makes it glow more brightly at all wavelengths. Thus the Sun is a much
    brighter infrared source than any terrestrial object, other than a laser.

    Cheers,

    Phil Hobbs
     
  19. Tim Williams

    Tim Williams Guest

    Other blackbody radiators, normalized by peak output.
    As I recall, they do. The sun emits very little microwave radiation, while
    the cosmic background temperature gives off copious amounts.

    (I suppose it might be possible to place microwave detectors on the sun
    (nevermind the physical difficulty of diodes operating at 7000K, but that's
    just an engineering problem), collecting the few picowatts of CBR that pass
    along, relaying that power back to a cold sink which thereby radiates more
    microwave radiation. Likewise, the cold sink transforms the visible
    radiation from the detector into additional microwave radiation.

    It's an interesting thought, but I'm sure that, if I ran the numbers, I'd
    discover that it doesn't come out over unity, which is how it ought to be,
    after all.)
    Infrared perhaps, but not far IR or microwave.

    Consider: if this were true, then celestial x-ray and gamma sources would be
    visible on telescopes (assuming there is a direct line of sight, which for
    energetic radiation, need not be). Many radio and x-ray sources are only
    visible due to visible-spectrum matter, as I recall.

    Tim
     
  20. Chuck

    Chuck Guest

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