Hi Ma, I'm wondering if you performed proper unit conversion. Let's say your td(I assume this is the time delay) is x ps/in(note that this is ps per inch), then the relationship is like following. Er=3D(vc*td)^2=3D(3e8*m/s*x*ps/in)^2=3D(3e8*m/s*x*ps/in*39.37*in/m)^2 So, your time and length dimensions are removed. Regards, TK -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of ma mu Sent: Tuesday, October 23, 2007 11:39 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Dielectric constant measuring=20 Hi , =20 I am trying to measure the dielectric constant value of our ckt at 100mhz -3 Ghz in our lab. I have measured it but the value is too low 2.5 ( expectiing value is between 3.2 to 3.5) . =20 I have used Iconnect software to measure the transient time for an electromagnetc pulse to travel the length of my transmission line. =20 and the formula I have used is following: td=3Dmeasured data=20 l=3Dlength of the transmission line Vc=3D velocity of light.=20 =20 Er=3D (Vc*Vc*td*td)(l*l) =20 the TDR I have used has 35 ps rise time .=20 =20 =20 please let me know why I did get this low value. or you could recommend me to find a way to get Er value. I will appreciate your help. =20 =20 Ma Steve, Thanks for the plug! Sometimes the best solutions are the easiest! Lee > [Original Message] > From: steve weir=20 > To:=20 > Cc: QU Perry=20 ; si-list > Date: 9/15/2007 12:10:47 PM > Subject: Re: [SI-LIST] Re: fiber-weave effect alive and well? > > In the shameless plug for someone else dept: Lee's book "Right the=20 > First Time Volume 2" does do a nice job of demonstrating the difference=20 > between various weaves including some good cross-section=20 > microphotographs and TDR plots. I think it is worth the price of the=20 > book for that information alone. > > Steve > Lee Ritchey wrote: > > The link to the Circuitree web site requires each person to register and > > obtain a password. > > > > It is true that the thinner weaves are the problem. > > > > I cover these weaves and results in Chapter 5 of Volume 2 of my book.=20 > > There are photos showing what the weaves look like compared to a 3.5 mil > > trace. Also show what vias do to very fast signals. > > > > Lee Ritchey > > > > > >=20 > >> [Original Message] > >> From: QU Perry=20 > >> To: si-list=20 > >> Date: 9/14/2007 12:25:54 PM > >> Subject: [SI-LIST] Re: fiber-weave effect alive and well? > >> > >> I would be interested to see a link as well. > >> > >> Jeff's paper on DesignCon2007 is convincing to me that this is something > >> we need to pay attention. Real life design will probably not be as bad > >> as the theoretical estimate since most of the diff pair routing we have > >> on the PCB is not likely to run a long length non-stop in parallel with > >> edge. The "jog" as is called in the paper is very common due to vias etc > >> and pretty random. > >> > >> Also from the data we got from PCB vendor, it appears that thinner > >> dielectric substrate the worse fibre weave effect as the gap between the > >> fiber is larger. Has this been looked at ? > >> > >> Regards > >> > >> Perry > >> > >> > >>=20 > > =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D =3D3D=3D > >=20 > >> = =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= 20 > >> > >> Perry Qu=3D20 > >> > >> Design & Qualification, Alcatel-Lucent Canada Inc. > >> > >> 600 March Road, Ottawa ON, K2K 2E6, Canada=3D20 > >> > >> DID: 613-7846720 Fax: 613-5993642=3D20 > >> > >> Email: perry.qu@xxxxxxxxxxxxxxxxxx=3D20 > >> > >> > >>=20 > > =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= 3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D =3D3D=3D > >=20 > >> = =3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D= 20 > >> > >> =3D20 > >> > >>=20 > >>> -----Original Message----- > >>> From: si-list-bounce@xxxxxxxxxxxxx=3D20 > >>> [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of=3D20 > >>> Aubrey_Sparkman@xxxxxxxx > >>> Sent: Friday, September 14, 2007 1:59 PM > >>> To: leeritchey@xxxxxxxxxxxxx; rdudek@xxxxxxxxxxxxxxx;=3D20 > >>> si-list@xxxxxxxxxxxxx > >>> Subject: [SI-LIST] Re: fiber-weave effect alive and well? > >>> =3D20 > >>> Would you like to share a link?=3D3D20 > >>> =3D20 > >>> =3D20 > >>> Aubrey Sparkman=3D3D20 > >>> Enterprise Engineering Signal Integrity Team=3D3D20 Dell, Inc.=3D3D20=3D20 > >>> Aubrey_Sparkman@xxxxxxxx=3D3D20 > >>> (512) 723-3592=3D3D20 > >>> "Discovery consists of seeing what everybody has seen and=3D20 > >>> thinking what nobody else has thought." - Jonathan Swift > >>> =3D20 > >>> =3D20 > >>> -----Original Message----- > >>> From: si-list-bounce@xxxxxxxxxxxxx=3D20 > >>> [mailto:si-list-bounce@xxxxxxxxxxxxx] > >>> On Behalf Of Lee Ritchey > >>> Sent: Friday, September 14, 2007 11:36 AM > >>> To: Russell S. Dudek Jr.; si-list@xxxxxxxxxxxxx > >>> Subject: [SI-LIST] Re: fiber-weave effect alive and well? > >>> =3D20 > >>> We already have a glass weave solution. Check my column in=3D20 > >>> the April issue of Circuitree magazine. > >>> =3D20 > >>> Lee Ritchey > >>> =3D20 > >>> =3D20 > >>>=20 > >>>> [Original Message] > >>>> From: Russell S. Dudek Jr.=20 > >>>> To:=20 > >>>> Date: 9/12/2007 1:10:28 PM > >>>> Subject: [SI-LIST] Re: fiber-weave effect alive and well? > >>>> > >>>> Steve, > >>>> =3D3D20 > >>>> I agree, Fiber Weave Effect (FEW) has most certainly been=3D20 > >>>>=20 > >>> confirmed by > >>> such > >>>=20 > >>>> research. However, there is a new change in the wind. I=3D20 > >>>>=20 > >>> have the=3D3D20=3D20 > >>>=20 > >>>> unique opportunity, as a technical liaison, to enable a=3D20 > >>>>=20 > >>> technology=3D3D20=3D20 > >>>=20 > >>>> that may put > >>>>=20 > >>> an > >>>=20 > >>>> end to FWE as a consideration in high-speed designs. We=3D20 > >>>>=20 > >>> all know that > >>> =3D20 > >>>=20 > >>>> the crux of the matter is the glass weave and its effect on=3D20 > >>>>=20 > >>> localized > >>> Er. > >>>=20 > >>>> Either get ride of the reinforcement layer completely or more=3D3D20=3D20 > >>>> challenging change the fundamentals of the glass weave fabrication > >>>>=20 > >>> process (GWFP). > >>>=20 > >>>> =3D3D20 > >>>> We have taken the more challenging (and fun) approach and = have=3D20 > >>>> rocked=3D3D20 the fundamentals the GWFP. I cannot disclose much the=3D20 > >>>> specifics of=3D3D20 the technology and our partners in such = an=3D20 > >>>>=20 > >>> open forum. =3D20 > >>>=20 > >>>> However, if=3D3D20 you are interested learning more feel = free=3D20 > >>>>=20 > >>> to contact=3D20 > >>>=20 > >>>> me and we can=3D3D20 get the proper NDAs in place to = facilitate=3D20 > >>>>=20 > >>> such a discussion. > >>>=20 > >>>> =3D3D20 > >>>> RD > >>>> =3D3D20 > >>>> Russell Dudek > >>>> Technology Specialist > >>>> Compunetics, Inc. > >>>> 700 Seco Road > >>>> Monroeville, PA 15146 > >>>> 412-858-6264 > >>>> rdudek@xxxxxxxxxxxxxxx > >>>> www.compunetics.com =3D3D20 > >>>> > >>>> To see where no one notices the contrast of white on white is =3D > >>>>=20 > >> an=3D3D20=3D20 > >>=20 > >>>> indispensable virtue of infinite potential. > >>>> > >>>> =3D3D20 > >>>> > >>>> > >>>> > >>>> ------------------------------------------------------------------ > >>>> To unsubscribe from si-list: > >>>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the=3D20 > >>>>=20 > >>> Subject field > >>>=20 > >>>> or to administer your membership from a web page, go to: > >>>> //www.freelists.org/webpage/si-list > >>>> > >>>> For help: > >>>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >>>> > >>>> > >>>> List technical documents are available at: > >>>> http://www.si-list.net > >>>> > >>>> List archives are viewable at: =3D3D20 > >>>> //www.freelists.org/archives/si-list > >>>> or at our remote archives: > >>>> http://groups.yahoo.com/group/si-list/messages > >>>> Old (prior to June 6, 2001) list archives are viewable at: > >>>> http://www.qsl.net/wb6tpu > >>>> =3D3D20 > >>>>=20 > >>> =3D20 > >>> =3D20 > >>> ------------------------------------------------------------------ > >>> To unsubscribe from si-list: > >>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >>> =3D20 > >>> or to administer your membership from a web page, go to: > >>> //www.freelists.org/webpage/si-list > >>> =3D20 > >>> For help: > >>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >>> =3D20 > >>> =3D20 > >>> List technical documents are available at: > >>> http://www.si-list.net > >>> =3D20 > >>> List archives are viewable at: =3D3D20 > >>> //www.freelists.org/archives/si-list > >>> or at our remote archives: > >>> http://groups.yahoo.com/group/si-list/messages > >>> Old (prior to June 6, 2001) list archives are viewable at: > >>> http://www.qsl.net/wb6tpu > >>> =3D3D20 > >>> ------------------------------------------------------------------ > >>> To unsubscribe from si-list: > >>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >>> =3D20 > >>> or to administer your membership from a web page, go to: > >>> //www.freelists.org/webpage/si-list > >>> =3D20 > >>> For help: > >>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >>> =3D20 > >>> =3D20 > >>> List technical documents are available at: > >>> http://www.si-list.net > >>> =3D20 > >>> List archives are viewable at: =3D20 > >>> //www.freelists.org/archives/si-list > >>> or at our remote archives: > >>> http://groups.yahoo.com/group/si-list/messages > >>> Old (prior to June 6, 2001) list archives are viewable at: > >>> http://www.qsl.net/wb6tpu > >>> =3D20 > >>> =3D20 > >>> =3D20 > >>>=20 > >> ------------------------------------------------------------------ > >> To unsubscribe from si-list: > >> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >> > >> or to administer your membership from a web page, go to: > >> //www.freelists.org/webpage/si-list > >> > >> For help: > >> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >> > >> > >> List technical documents are available at: > >> http://www.si-list.net > >> > >> List archives are viewable at:=20 > >> //www.freelists.org/archives/si-list > >> or at our remote archives: > >> http://groups.yahoo.com/group/si-list/messages > >> Old (prior to June 6, 2001) list archives are viewable at: > >> http://www.qsl.net/wb6tpu > >>=20 > >>=20 > > > > > > ------------------------------------------------------------------ > > To unsubscribe from si-list: > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > > > or to administer your membership from a web page, go to: > > //www.freelists.org/webpage/si-list > > > > For help: > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > > > > List technical documents are available at: > > http://www.si-list.net > > > > List archives are viewable at:=20 > > //www.freelists.org/archives/si-list > > or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages > > Old (prior to June 6, 2001) list archives are viewable at: > > http://www.qsl.net/wb6tpu > >=20 > > > > > > > >=20 > > > --=20 > Steve Weir > Teraspeed Consulting Group LLC=20 > 121 North River Drive=20 > Narragansett, RI 02882=20 > > California office > (408) 884-3985 Business > (707) 780-1951 Fax > > Main 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Mail has the best spam protection around=20 http://mail.yahoo.com=20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: =20 //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu