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  • EEVblog #202 – EMC RF Anechoic Test Facility Tour

    Posted on September 22nd, 2011 EEVblog 20 comments


    Dave goes on a tour of EMC Technologies new $1.8M RF Anechoic Test chamber used for automatic and product testing for EMC emissions and susceptibility.
    Also their other test chambers like the GTEM (Gigahertz Transverse Electromagnetic) test facility.
    Thanks to Rob Weir (Yes, he’s a New Zealander :->)
    www.emctech.com.au

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    • Andrew Vuong

      Holy crap ._.

    • John Dowdell

      Awesome awesome video. And props to them for letting you poke around. So… $10 to $15 a tile eh? I wonder if they’d sell them in ones and twos :) shipping would be the killer though.

      • http://www.emctech.com.au Chris Zombolas

        Actually, the ferrite tiles cost around US$6 each. At 10cm square, it works out to around $3600 per sq m.
        The s called “cardboard” cones actually have a metal film inside and are not flammable. They cost around $400 per square metre but are not effective below 800 MHz. The older blue polyurethane cones are impregnated with carbon. They are effective but are heavy and flammable. Some labs have suffered fires when testing at 200 V/m.

        • http://www.eevblog.com EEVblog

          Thanks for the added details Chris, and for sharing your facility with us!

        • http://www.emctech.com.au Chris Zombolas

          Don’t knownwhere the 400 Mhz came from!! May be it wa slate in the night BUT it should read 30MHz to 1000 MHz

    • Kart (not that Karl, the other Karl)

      Did I hear that right? Whenever you went into a chamber your cell phone interfered with he camera audio? It would make sense, the cell phone ramping up its power, because it figures the power form the cell phone tower got weak.

    • adam lumpkins

      Dave I love it when you guys walked into the chamber the echo was gone!!!!! What were the cones made of?

    • adam lumpkins

      ok lol I didnt hear that the firstime cardbord!!!

    • http://kj6ead.hackhut.com KJ6EAD

      That’s a nice facility. It would have been great to see a typical unit under test as a demo.

      Two suggestions for improvement: 1; Put a radio microphone on your guest so we can hear him and 2; Edit for length.

    • http://www.emctech.com.au Chris Zombolas

      The Ferrari is definietly not EMC’s company car. Note that it was in the visitors spot. Most successful companies use our services, another reason why they are successful!!
      Chris Zombolas-MD.

    • f4eru

      nice chamber, 10m class ?, non-flammables absorbers…

      it doesn’t seem to have a turntable for vehicles.

      I used a 30m class chamber in Japan, with a turntable capable of turning a truck, that was really impressive !

      Also, i saw photos from an EMC chamber which burned down including half of the EMC company after a light fall down on flammable absorbers, crazy. the old flammable absorbers burn so fast, it nearly explodes !

      The FCC standard uses this crazy metal ground plane, which makes little other sense than to cost less money than absorbers ! European standards specify free space but allow FCC style tests (with a conversion ratio)

      when you test antennas, you need a fully anechoic chamber, which is more difficult to find…

      • Ed Price

        You need to recalibrate your crazy sensor.

        The ground plane on an OATS is intended to standardize test sites. Not everybody has similar conductivity dirt, so the GP provides a uniform and standard working surface. If you didn’t have that GP, you would never get good field uniformity and decay over the working area on your OATS.

        Urethane foam RF absorbers are not “crazy” flammable, certainly no more than a urethane pillow. Yes, they will burn, but they are not as dangerous as you think. Certainly in the USA, fire marshalls and/or the insurance people will see that your chambers have fire suppressant systems. (Those systems often present a major technical and financial consideration in building a SA chamber.)

      • Ed Price

        When you calibrate antennas, you often don’t have a frequency coordination issue, so you can test them on an open range site. Professional antenna cal labs will often be located in remote physical locations to take advantage of a combination of low ambients and wide open spaces.

    • f4eru

      other remark : the GTEM is just a square coax which gets bigger while keeping the same impedance (50 ohm). So it’s a coax cable you can walk inside !!

      • http://www.eevblog.com EEVblog

        Great analogy!

    • john McAllison

      Absolutely… awesome…

    • http://www.neelfirst.com Neel

      Cool video! I used to work at a company that purchased a similar system for EMC RF compliance testing in-house. I was supposed to be the one in charge of setting it up but then I left. Oops!

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    • Ed Price

      Nice overview.

      I cringed when you finger-squeezed the tips of the pyramidal RF absorbers; every visitor to my lab had to do exactly the same thing, and the tips of my absorbers were worn ragged.

      The pyramidal RF absorbers are an open-cell urethane foam, with a lossy material literally washed through the cell structure on manufacture. The water is then dried, depositing the lossy material throughout the foam. So, the outer paint has nothing to do with the absorber performance (except to degrade it a bit at the upper frequency limit). By tradition, they were painted blue, but then some smart person noticed that a chamber could be much more light and airy if they painted there pyramids gloss white. OTOH, royal blue hides the dust better; who wants to vacuum clean every absorber facet twice a year?

      The metal on the door seals is beryllium copper fingerstock.

      The TEM cell will actually work down to DC; it’s just that nobody seems to need a DC immunity test.

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