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Small EMC antenna

Discussion in 'Electronic Design' started by Joerg, Sep 28, 2007.

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  1. Joerg

    Joerg Guest

    Hello Folks,

    Many of you know the drill. When doing pre-compliance EMC work you
    either need to bring or rent a bicone and a log-perdiodic. Bringing is a
    challenge. Check it and chances are you'll find it turned into a pretzel
    at the baggage claim. Or it ain't there at all but en route to some
    tropical paradise. Taking a collapsed version in the carry-on is no
    longer a real option because that really makes the neck hair of the TSA
    guys stand up. My EMCO near field kit alone raises enough attention as
    it is.

    There ain't much out there in terms of miniaturized wideband stuff and
    what is available is rather pricey. Do you know any web links about
    building your own? With some crude performance curves along with it?

    Similar to this unit:

    Preferably something that could go to 2.45GHz . It doesn't have to be
    very efficient because most pre-compliance work happens at the three
    meter range anyhow.
  2. Fred Abse

    Fred Abse Guest

    Pack it properly and send it ahead by FedEx?
  3. Joerg

    Joerg Guest

    In a wooden crate, maybe. Else it can break just as easy. A few months
    ago I saw a formerly pristine HP3585 that must have had a head-on with
    the tarmac. Even the deflection plates in the CRT had torn off. That can
    make grown men cry, they don't build analyzers of that caliber anymore.
    That delayed our project substantially.
  4. Charles

    Charles Guest

    I assume you know about stuff like this:
  5. John Larkin

    John Larkin Guest

    This looks tough, sort of a cross berween an antenna and a surfboard:

    Not real expensive, I seem to recall. I'd go for the transparent,
    hand-polished version... all the girls would swoon.

  6. Fred Abse

    Fred Abse Guest

    Aargh! The person responsible for that should be hung by the testicles and
    have his liver pecked out by vultures!
  7. Joerg

    Joerg Guest

    Sure. But show up at the TSA check point with that kind of stuff and
    there will be a lengthy chat, plus maybe a missed flight. As checked
    baggage it's the usual white-knuckle flight. Will it be there when I
    reach the conveyor belt?

    There has got to be something simpler and much cheaper. Pre-compliance
    does not require 3dB accuracy at all.
  8. Joerg

    Joerg Guest

    Yes, that's one option. Rumors have it they'll even make a
    pre-compliance handheld soon with the right frequency range. Their chip
    designer is on the German equivalent of s.e.d. so we hear the rumors
    first :)

    But it would have to be self-imported.
  9. Joerg

    Joerg Guest

    Ah, yes! Thanks. Now I'll scope out a place where I can rent one and try
    it out on the next pre-compliance job in a few weeks. Plus it's a US
    source. Sweet.

    Looks like it would be a self-import, plus the $/GBP rate ain't so
    favorable these days.

    As long as it's reasonable. If not, and if I have my druthers, I'll
    calculate one and build it. Preferably totally open so the TSA guys can
    take a good look and feel confident that it's passive and harmless.
    Stuff with batteries in there isn't too practical these days if you must
    fly to your client. Unless it's something a lot of people have like
    music players.
  10. You won't be able to do any valid measurements without a shielded room
    unless the EMI from your device is really bad. The noise from the
    ambience obscures the results. Since you will be able to spot only the
    major problems, pretty much any antenna will do for that purpose. Of
    course, the basic antenna theory applies.

    Vladimir Vassilevsky
    DSP and Mixed Signal Design Consultant
  11. Joerg

    Joerg Guest

    I know, it's just for pre-compliance. I've had pretty good luck so far
    doing that anywhere, always hoping it's not raining and we can measure
    out on the lawn away from computers and stuff. It works. Except that
    sometimes you'll have to deal with nosy people walking by, or animals.
    Once even a deer that decided that the grass between my antenna and the
    DUT was the best in the whole region. Totally unfazed by clicking relays
    and all that. Even left a "souvenir" for us.

    As for the antenna, yes, I can calculate my own. I was just hoping
    someone had already kludged and measured one out and posted the "recipe"
    on the web :)
  12. Rich Grise

    Rich Grise Guest

    Did you hear the one about the guy who caught another guy in bed with
    his wife? He subdued the guy, took him out to the shed, and nailed
    his dick to the workbench. He then produced a large butcher knife,
    at which point the philanerer said, "You're going to cut my dick off?"
    And guy A hands guy B the knife and says, "No, I'm going to burn the
    shed down. _You're_ going to cut your dick off."

  13. Joerg,
    I get the impression, you're not used to imports.
    A direct import is usually much better than going
    through one of those dealers. They just multiply
    the price without actually doing much. I'm used
    doing my own imports multiple times a year.

  14. Joerg

    Joerg Guest

    Or, on something large I don't mind. Except that the power plugs don't
    jibe, got a scope from England and it came with those unwieldy plugs
    they have ;-)
  15. John Larkin

    John Larkin Guest

    They make scopes in England?


  16. No, they deserve something even worse. Locked in the same cell with
    Radium, Eeyore, w_tom, brad_gurth and Phil Allison for eternity.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  17. Fred Abse

    Fred Abse Guest

    That comes under "Cruel and unusual punishments".
  18. Joerg

    Joerg Guest

    Not anymore since the Telequipment days I think. It was made in China
    but only in Europe was there a decent deal to be found. Then a common
    weirdness applied: It was much cheaper for export than for the
    Europeans. I have seen that happen a lot.
  19. JosephKK

    JosephKK Guest

    Joerg posted to
    OK, from context and some googling i can see that it is some kind of
    network analyser. I sure would like a one paragraph description.
    Manuals for fancy eaglesoft / genisys software packages just are not
    doing it for me. (available from the Agilent site)
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