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  1. #1
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    Unhappy MICROWAVE ANTENNA'S

    Gentlemen,
    We have an account with some rooftop units. Recently microwave antenna have been installed. They posted a danger sign not to be exposed for long periods????????????

    Do any of you have anything like this at other sites?
    Any literature for reading?
    What does your company do to service the equipment?????????
    "My hands are for sale"

  2. #2
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    have been on places like that..i stayed as far away as i could. the amount of "damage" that can be done would be based on power and frequency. I have done work in factories that use frequency's to produce heat..signage and a line on the ground saying do not pass if u have a pace maker.

  3. #3
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    Do you ever notice people in factory working near the frequency emitters?
    "My hands are for sale"

  4. #4
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    all the time...was used to fuse 'fabric" to wire used in large motors. the operators would sit back and watch the wire. Same area had control cabinets with small ac systems..worked on them occasionally. But those use a different frequency than microwave antennas...those are designed to pass threw buildings and you.

  5. #5
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    Another site I posted on asked about RF radiation. Here is what I gave them.

    The US army knows a thing or two about RF radiation and the effects on the human body.

    Protection of DoD Personnel from Exposure to
    Radiofrequency Radiation and Military Exempt Lasers

    http://cryptome.org/dodi6055-11.htm

    More food for thought.

    ELECTROMAGNETIC RADIATION HAZARDS (U)(HAZARDS TO PERSONNEL, FUEL AND OTHER FLAMMABLE MATERIAL)
    NAVSEA OP 3565/NAVAIR 16-1-529 VOLUME 1

    http://www.cpp.usmc.mil/mcas/docs/NA...20Vol.%201.pdf
    I would ask the people that operate the antenna what is acceptable. They should know and not have you guessing.

  6. #6
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    timebuilder is offline AOP Committee/Professional Member*
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    Even though some studies are in conflict, it is generally accepted that exposure to RF at power levels beyond a few dozen watts is something to be avoided. Higher frequencies that cause tissue heating, such as microwave range RF, are particularly dangerous. Most broadcast RF engineers I know do not "visit the transmitter" unless they must, as they are usually clustered together with others in what is called a "farm," and let me tell you, if you have a bunch of TV and radio stations all blasting out thousands of kilowatts of RF (total output) you have a real exposure while there.

    Most units found on rooftops (as opposed to antenna structures) are very directional and you simply do not want to stand with the radiator pointing at you for more than a second or two, in order to limit exposure.

    If you have medical devices implanted, like a pacemaker, I would not allow the body to be aligned with the radiator, and avoid the location from any vector by 30 feet, if possible. RF decreases by the square of the distance when the device radiates in all directions, and microwave antennas are so directional that they do not follow that rule, so even at a distance of dozens of feet, the emission can be almost as strong as standing right in front of it.

    So, with a directional RF transmitter, avoiding alignment with the radiator is the key safety concept.
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  7. #7
    Join Date
    Jan 2002
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    Seattle/Bothell
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    microwaves are bad news. My guess is that your building recently acquired a lease from one of the cell phone carriers. Keep away from in front of microwave antenna. Especially keep away from Omni directional antennas. Those will give you a headache pretty quick

  8. #8
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    Get in get out and GET OUT. Rip and dip. Move it or loose it. Better safe than sorry. Honestly I service a few chillers on roofs along side misc cell phone com towers bla bla bla the service guys "for the towers" tell me not to stand in front of them and not to stand right up to em and I'll be OK. I will tell you that it can't be good for long periods of time. I use to work on allot of "research" projects for scientists, universities and so on one particular project involved chirogenics and whatever the hell they were doing with frequency's and magnetics erased the magnetic tape on my cc and license, and my cell phone went bye bye.
    “It takes courage to grow up and turn out to be who you really are.”

    - E.E. Cummings

  9. #9
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    Read the signage - usually there is an 800 number. It may take a bit (various personnel and phone menus), but they'll turn off the transmitter while you're on site.
    UA LU 562

  10. #10
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    Do all micro ant have the shape of a dish or rectangle? Do any have the shape of the old style tv ant you see on a house roof.

    This is a coast guard intallation.
    "My hands are for sale"

  11. #11
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    Quote Originally Posted by mrhvacmechanic View Post
    Do all micro ant have the shape of a dish or rectangle? Do any have the shape of the old style tv ant you see on a house roof.

    This is a coast guard intallation.
    Yes they take those shapes also.

    On navy ships when there really is no way to stay out of the way of the beam they have the personnel wear a wire mesh suit.

    Might be time to break out the aluminum foil hat and underwear.

    Just kidding there.

  12. #12
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    There was a good discussion on this site in May 2009 about this topic here: http://hvac-talk.com/vbb/showthread.php?t=278742

    2nd page has some information on the signs and what the colours on them mean.

  13. #13
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