RE: [SI-LIST] : "Picket Fence" (Via Fence) for increasing isolati

Knighten, Jim L (JK100005@exchange.SanDiegoCA.NCR.COM)
Thu, 2 Sep 1999 12:30:02 -0700

Elya,

This is an interesting topic! We have never used the "picket fence," as you
call it reduce crosstalk, but rather have used it to stitch ground planes
together at the edge of boards.
The only published reference that I am aware of on this subject is [Kim,
1995] that I cite below.
Kim shows that crosstalk attenuation in excess of 20 dB can be obtained with
a double row of plated hole vias with 30 mil diameters and 100 mil spacing.
His setup had parallel microstrip traces with the via fence between them.
Kim was concerned about frequencies between 500 MHz and 6 GHz.
Kim, Myung-Kul, "Crosstalk Control for Microstrip Circuits on PCBs at
Microwave Frequencies," IEEE 1995 International Symposium on Electromagnetic
Compatibility, pp. 459-464.
Please share whatever wisdom you glean from this quest.

Jim
________________________________________________________
Dr. Jim Knighten e-mail: Jim.Knighten@SanDiegoCA.NCR.com
<mailto:Jim.Knighten@SanDiego.NCR.com>
Senior Consulting Engineer
NCR
17095 Via del Campo
San Diego, CA 92127 http://www.ncr.com <http://www.ncr.com>
Tel: 858-485-2537
Fax: 858-485-3788

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-----Original Message-----
From: Elya B. Joffe [mailto:ebj@netvision.net.il]
Sent: Thursday, September 02, 1999 10:44 AM
To: Elya B. Joffe; si-list@silab.eng.sun.com; Vinu
Arumugham; yehuda@zoran.co.il; John Lin - TAO; Howard Johnson; Gert Winkler;
Ron Matthews; Roland F. Portman
Subject: [SI-LIST] : "Picket Fence" (Via Fence) for
increasing isolation between

Dear Members,

I am involved in a project where we must apply the technique
of
"Picket Fence" (Via Fence) for increasing isolation between
conductors on a PCB.

I cannot find any refercnes (papers, books, etc.) on that
issue. Are
you familiar with anything on that issue? The problem,
basically, is
- how much isolation can we get between conductors embedded
between
ground planes, or between ground and power planes, when they
are
"isolated" by a "picket/via fence".

If you have come across such material, or references, I
would be
grateful if you could refer me to them. I have gone through
the
"classics" and could find nothing there, and I need some
references
for the work we are involved in...

Elya B. Joffe - EMC Engineer

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