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 > > > > > >>>>> ------------------------------------------------------------------ > >>>>> To unsubscribe from si-list: > >>>>> 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