[SI-LIST] Re: Traces don't cause EMI - really?

  • From: Doug Brooks <doug@xxxxxxxxxx>
  • To: si-list@xxxxxxxxxxxxx
  • Date: Sun, 12 Oct 2003 19:58:51 -0700

To keep the record straight, that paper was intended to measure if there 
was a *difference* in EMI as a function of trace corner geometry --- i.e. 
45 degree vs 90 degree corners. It was not designed to measure how much 
radiation existed.

What was reported was a comparative result between geometries, not an 
absolute result.

Doug Brooks




At 05:59 PM 10/12/03 -0700, Lee Ritchey wrote:
>Charles,
>
>One of the papers I refer to is on my web site as well as That of Doug
>Brooks.  It is titled "90 Degree Corners, The Final Turn".
>
>The measurements were made in the lab at UMR.
>
>If there is data out there that contradicts this, it would be good to share
>it.
>
>It's not hard to take a near field probe and run it along traces that are
>on outer layers of a PCB with solid planes and get similar answers.
>
>Lee
>
>
> > [Original Message]
> > From: Grasso, Charles <Charles.Grasso@xxxxxxxxxxxx>
> > To: Lee Ritchey <leeritchey@xxxxxxxxxxxxx>; si-list@xxxxxxxxxxxxx
><si-list@xxxxxxxxxxxxx>
> > Date: 10/10/2003 9:20:28 AM
> > Subject: [SI-LIST] Traces don't cause EMI - really?
> >
> > Lee,
> >
> > I was thumbing through some of the diff pair thread and ran across
> > this comment that you had made:
> >
> > "Second, traces that run over continuous planes don't cause EMI,
> > differenrtial or otherwise. Again, there are many papers that demonstrate
> > this as well."
> > I am sure you didn't mean this. There a many papers, notably by Bob
>Dockey,
> > that clearly
> > show the diople-like profile of a trace over a continuous ground plane.
>The
> > paper
> > also showed that, depending on the size of the board, the emissions can
> > exceed the
> > FCC Class B limits - thats one trace over a continuous ground.
> >
> > Can you please expand on your comment ?
> >
> >
> > Best Regards
> > Charles Grasso
> > Senior Compliance Engineer
> > Echostar Communications Corp.
> > Tel:  303-706-5467
> > Fax: 303-799-6222
> > Cell: 303-204-2974
> > Email: charles.grasso@xxxxxxxxxxxx; <mailto:charles.grasso@xxxxxxxxxxxx; >
> >
> > Email Alternate: chasgrasso@xxxxxxxx <mailto:chasgrasso@xxxxxxxx>
> >
> >
> >
> >
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>
>
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