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Text Book on Ambient EMF Measurements

Discussion in 'Electronic Design' started by [email protected], Mar 23, 2013.

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  1. Guest

    Can anyone suggest a good text book, or online publication, that
    explains in detail the procedures for detection and measurement of
    ambient RF?

    IOW out in the field, not in the lab.

    Our antenna guy just passed away, so we need to get up to speed on

    Thanks for any advice.

    Richard Jones
  2. Fred Abse

    Fred Abse Guest

    AFAICS, energy harvesting from RF fields could be regarded as theft.

    It is impossible to remove energy from a field without disturbing that

    The field was put there, *and paid for*, by someone else, with a specific
    purpose. The owner has the right to expect that field not to be
    deliberately disturbed.

    Extracting energy can be said to be depriving the owner of his property,
    for the gain of another.

    Ambient RF energy is not a free resource. Somebody bought and paid for it.
  3. Fred Abse

    Fred Abse Guest

    Of course not. The intrinsic impedance of free space is 120*pi ~ 377 ohms,
    but I guess you knew that,already.

    Measure the field in front of, and behind a receiving antenna, and you'll
    see the difference.
    No it isn't garbage, it's a necessary part of an operable system.

    The station own can probably sue
    Stolen goods are stolen goods, even if you can't identify the owner. The
    act of appropriation with intent to deprive someone else of lawful benefit
    is sufficient. It's not an FCC matter, it's purely common law.
    You admit that it's not selective, what then of ten thousand users each
    trying to extract 50 milliwatts from the field of a 500 watt transmitter?

    Damages aren't the issue, it's a criminal, not a civil matter. Unlawfully
    taking with the intent to deprive the owner of possession.
    I repeat, not a civil damages matter. No less criminal than extracting
    energy from fields surrounding transmission lines.
    That dog won't hunt.
  4. tm

    tm Guest

    If you are getting 50 mW from a 500 W transmitter, you are trespassing.

  5. To the same extent that using my house as a transmission route could be
    regarded as trespass :)
  6. Fred Abse

    Fred Abse Guest

    Whether you steal a Popsicle, or a million dollars, in law it is still
    theft, with punishment that may or may not be commensurate, depending on
    the jurisdiction.
    In many cases, the owner never recovers possession, the thief having spent
    the proceeds, but the thief still goes to jail.
  7. Fred Abse

    Fred Abse Guest


    Receiving antenna aperture?

    Show your working.
  8. Tim Williams

    Tim Williams Guest

    Some strange taxation methods were considered early on. Apparently there
    was a tax per tube law in Germany I think, so they invented the forerunner
    of the MK484 radio-in-one. Vacuum sealed resistors and several tube
    sections all in one envelope, just add coils. Although the production
    costs, as you might imagine, were more than a bit worse than the tax
    itself, so it never went into production.

  9. Robert Macy

    Robert Macy Guest

    join the IEEE group that discusses these matters and post your
    question there.
    it's a combination of safety AND EMC, most of the questions appear to
    be about EMC.
    you'll get answers that'll make you think everything from 'say what?!'
    to "wow! didn't know that!"

    tacked at the bottom of every email posted on the group:

    This message is from the IEEE Product Safety Engineering Society emc-
    pstc discussion list. To post a message to the list, send your e-mail
    to <[email address munged by me... emc-pstc AT
    ieee DOT org]>

    All emc-pstc postings are archived and searchable on the web at
    Graphics (in well-used formats), large files, etc. can be posted to
    that URL.

    List rules:

    For help, send mail to the list administrators:
    Scott Douglas <[email address munged by me.. emcpstc AT
    socal DOT rr DOT com]]>
    Mike Cantwell <[email address munged by me.. mcantwell AT
    ieee DOT org]>
  10. John S

    John S Guest

    Aren't they already regulating receivers? I think it is illegal to
    manufacture cellular frequency receivers. Yes?
  11. brent

    brent Guest

    When I first started my career I worked with a guy who was at the very
    end of his career. He did a lot of radar work during WWII in
    England. He had a story about a radar they had set up and they knew
    the antenna pattern was not behaving the way it was supposed to. He
    said it turned out that a nearby farmer had somehow figured out how to
    run a big loop of wire through his barn (near the antenna) and was
    somehow able to generate power to light bulbs in his barn. Needless
    to say, the gov't made him take down his free power generating
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