# Re: [SI-LIST] : Regarding Slots ...

From: Christian Schuster ([email protected])
Date: Mon Apr 24 2000 - 23:06:35 PDT

Hi there,

if it's still of interest ... here's the reference
to the below mentioned article:

H. Liaw and H. Merkelo,
"Crossing the Planes at High Speed",
IEEE Circuits & Devices Magazine,
vol. 13, no. 6, pp. 22-26, November 1997

very well written. It helped me a lot to understand
what's going on.

By the way, in this article it seems to me that the FDTD
method was used to clarify the mode conversion process.
So let me give you another reference that uses FDTD to address
a similar issue:

S. Van den Berghe, F. Olyslager, D. De Zutter,
J. De Moerloose and W. Temmerman,
"Study of the Ground Bounce Caused by Power
Plane Resonances",
IEEE Trans. EMC, vol. 40, no. 2, pp. 111-119, May 1998

During my research as a Ph.D. student I used the FDTD method
as well for such problems and I found it very useful.

Best regards,

Ch. Schuster

Dan Swanson wrote:
>
> Doug,
>
> I was not looking for an explanation,
> just trying to give
> the person a reference to one
> of Merkelo's articles.
>
> Dan
>
> -----Original Message-----
> From: Doug McKean [SMTP:[email protected]]
> Sent: Monday, April 24, 2000 1:44 PM
> To: [email protected]
> Subject: [SI-LIST] : Regarding Slots ...
>
> I've seen Doug Smith do an excellent demonstration
> of the "trace crossing a slot" phenomena.
>
> Analytically, if you borrow Babinet's method from
> optics, a slot is the complement of a wire. In
> principle, a slot is the dual of wire and can
> even be drawn as such. Whereas the wire is current
> driven, a slot or more generally an aperture, is
> voltage driven. As long as an electric field is
> developed across the slot, it will radiate. Return
> currents from the trace across a slot accomplish
> this quite nicely. Good to keep traces away from
> slots and only cut up ground planes if absolutely
> necessary.
>
> Slots in product housings can be another matter
> if return currents develop a voltage across them.
> Where the directivity of a simple dipole is about
> 1.5 or so, the directivity of a slot can run upwards
> much higher by roughly a factor of 10 or so. So,
> given roughly the same amount of power, slots become
> more of an issue than wires during emissions testing.
>
> For a more formal mathematical analysis, might I
> suggest _Elements of Electromagnetics_ by Rao from
> Prentice Hall copyright 2000, ISBN 0-13-013201-2.
> Excellent discussion.
>
> Regards, Doug McKean
>
> Dan Swanson wrote:
> >
> > I remember one article in the past year or two
> > in IEEE Circuits and Devices Magazine.
> > Showed coupling of energy from a trace that crosses
> > a split ground plane. Coupling into slot mode was
> > clearly evident.
> >
> > Dan
> >
> > Dan Swanson EMAIL: [email protected]
> > Bartley R.F. Systems TEL: (978) 241-1091
> > 38 Water Street FAX: (978) 388-7077
> > Amesbury, MA 01913

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