From: Bill Owsley (email@example.com)
Date: Mon Jun 04 2001 - 12:34:48 PDT
At 11:16 AM 06/04/2001 -0700, Chris Rokusek wrote:
>Your first paragraph sounds good to me.
>Something else that to consider is that with parallel termination, the wave
>flows down the line without a reflection but with source termination the
>wave has to travel _twice_ as far before it is absorbed. This seems loosely
>like doubling the loop area.
not quite, but the time involved is doubled...
> Sounds like a good case for
>[mailto:firstname.lastname@example.org]On Behalf Of RMELLISON@aol.com
>Sent: Sunday, June 03, 2001 8:05 PM
>To: email@example.com; firstname.lastname@example.org
>Subject: Re: [SI-LIST] : Antenna Problem on the Board
>To Chris Rokusek, Jian-X. Zheng, Jason Leung, Andrew Martwick and others.
>Thanks for the feedback.
>The replies got me to really thinking about radiation and impedance. I went
>to my ARRL handbook to check out the quarterwave transformer reasoning, and
>this seems valid for a special case. But after reading a new book
>(Controlling Radiated Emissions by Design by Michel Mardiguian), I'm more
>convinced than ever that it is not the higher impedance that gives rise to
>greater EMI--it's the height of the trace above the ground plane that is the
>governing factor. The common assumption of the replies was that a higher
>impedance was caused by a larger height above the ground plane. Obviously
>you can get higher or lower Zo by varying the width of the trace while
>holding h constant. In this instance, I would say that for a given voltage
>across the transmission line, the lower impedance line would produce more
>due to higher line current. This is stated various places in Mardiguian's
>Nobody replied to my question about the radiation comparison of source
>terminated lines to end terminated lines. It seems to me that since you
>half as much current in a source terminated line, the EMI should be half as
>much as a parallel terminated line would produce. Does anyone agree with
>I appreciate the help.
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Bill Owsley, firstname.lastname@example.org
7025 Kit Creek Road
RTP. NC. 27709
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