[SI-LIST] Re: Right Angle Bends
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>, "Doug Brooks" <dbrooks9@xxxxxxxxxxxxxxx>
- Date: Fri, 15 Jul 2011 11:48:54 -0700
Doug,
Thanks for chiming in! I think we decided to do those tests at one of the
PCB Design Conferences in the late 1990s.
Myths are very hard to kill as this proves. Especially when experts don't
vet their info before publishing it! This is one of the reasons I started
this thread. One more attempt to get the record straight. Suppose we will
ever get this thing killed?
Lee
--------------------------------------------------
From: "Doug Brooks" <dbrooks9@xxxxxxxxxxxxxxx>
Sent: Friday, July 15, 2011 10:56 AM
To: <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: Right Angle Bends
> The origins go WAAAAAAAY back.
> We wrote our paper
> "90 Degree Corners; The Final Turn" trying to debunk this in 1998. It
> can be found in the articles section at http://www.ultracad.com
>
> The original concern may go back as far as 50 years with microwave
> people, but has been soundly debunked by many people in the last 10-15
> years.
>
> Doug
>
>
>
> At 10:43 AM 7/15/2011, Lee Ritchey wrote:
>>None of these calculations are substantiated by actual measurements.
>>
>>There are several published works with actual testing out to 20+ GHz
>>measuring signal traces that show there is no detectable effect on signal
>>quality.
>>
>>I have a half dozen test PCBs which have been used to make the same
>>measurements and I have published the results as well as shown them to
>>8000+
>>students in my public and private classes.
>>
>>Our industry has a problem with people doing simulations from which
>>conclusions are drawn without validating the simulations. Often, as in
>>the
>>case of right angle bends, much time and money is spent by designers
>>making
>>something go away that is of no consequence.
>>
>>Simulations without validation can be very dangerous.
>>
>>Lee Ritchey
>>
>>
>>
>>--------------------------------------------------
>>From: "Zabinski, Patrick" <zabinski.patrick@xxxxxxxx>
>>Sent: Friday, July 15, 2011 9:46 AM
>>To: <si-list@xxxxxxxxxxxxx>
>>Subject: [SI-LIST] Re: Right Angle Bends
>>
>> > Here are a few of the earlier references on the topic.
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > TITLE Calculation of Microstrip Bends and Y-Junctions With Arbitrary
>> > Angle
>> > AUTHOR Reza Mehran
>> > SOURCE IEEE Transactions on MTT, MTT-26
>> > DATE June, 1978
>> > PAGES 400-405
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > TITLE Microstrip - A New Transmission Technique for the Kilomegacycle
>> > Range
>> > AUTHOR D. D. Grieg & H. F. Engelmann
>> > SOURCE Proceedings of the IRE
>> > VOLUME 40
>> > DATE December, 1952
>> > PAGES 1644-1650
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >
>> > These offer related info.
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > TITLE Equivalent Circuit Modeling of Interconnects From Time-Domain
>> > Measurements
>> > AUTHOR Jyh-Ming Jong, Bozidar Janko, and Vijai Tripathi
>> > SOURCE IEEE Trans. on CHMT
>> > VOLUME 16
>> > NUMBER 1
>> > DATE February, 1993
>> > PAGES 119-126
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > TITLE Equivalent Circuits for Discontinuities in Balanced Transmission
>> > Strip Lines
>> > AUTHOR Arthur A. Oliner
>> > SOURCE IRE Trans Micorwave Theory & Techniques
>> > VOLUME MTT-3
>> > DATE March, 1955
>> > PAGES 134-143
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > TITLE Experimental Determination of the Properties of Microstrip
>> > Components
>> > AUTHOR Maurice Ardit
>> > SOURCE Electrical Communication
>> > VOLUME 30
>> > DATE December, 1953
>> > PAGES 283-293
>> >
>> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> > TITLE Time-Domain Characterization of Interconnect Discontinuities in
>> > High-Speed Circuits
>> > AUTHOR Jyh-Ming Jong and Vijai K. Tripathi
>> > SOURCE IEEE Trans on CHMT
>> > VOLUME 15
>> > NUMBER 4
>> > DATE August, 1992
>> > PAGES 497-504
>> >
>> > ~~~~~~~~~~~~<done>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >
>> > Enjoy,
>> > Pat Zabinski
>> > Mayo Clinic
>> >
>> > -----Original Message-----
>> > From: si-list-bounce@xxxxxxxxxxxxx
>> > [mailto:si-list-bounce@xxxxxxxxxxxxx]
>> > On Behalf Of Lee Ritchey
>> > Sent: Friday, July 15, 2011 11:33 AM
>> > To: si-list@xxxxxxxxxxxxx
>> > Subject: [SI-LIST] Re: Right Angle Bends
>> >
>> > Does anyone know the origin of the myth that right angle bends cause
>> > signal integrity problems?
>> >
>> > I though this myth had died a long time ago, but had a conversation
>> > last
>> > week with a well known fabricator who was told by a customer that right
>> > angle bends were a no no.
>> >
>> > This was a customer who should know better.
>> >
>> > Lee Ritchey
>> > Speeding Edge
>> >
>> >
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