Charles, The document I have, the one sited by Larry, FIgure 4 is a placement of antennas. What document do you have? The conclusion in the document I have makes no such statements. Lee > [Original Message] > From: Charles Grasso <cgrassosprint1@xxxxxxxxxxxxx> > To: <leeritchey@xxxxxxxxxxxxx>; Larry Barnes <larry.barnes@xxxxxxxxxx>; <si-list@xxxxxxxxxxxxx> > Date: 10/19/2003 7:21:16 PM > Subject: RE: [SI-LIST] Re: Traces don't cause EMI - really? > > Lee I am astounded at your comments. If you would glance at Figure 4 > (Emissions from a reference PCB without cables) you will see that > the Y-axis is numbered and (although not listed) is intended to be in > dBuV. If you look at the FCC Class B limit (superimposed on the > graph) I think you'll agree that the reference board actually FAILED > Class B at around 300MHz. I'd say that was pretty significant. > So, again, you are wrong to assert that the detected emissons > are not large enough to cause concern. > > I have modeled this board in Ansoft HFSS and got the same > results. > > Did you read the Conclusion? > > CONCLUSION: A multilayer PCB with a solid ground plane produced > radiated emissions similar to a dipole antenna. > SO Traces over planes DO cause emissions. > The emissions are from the PCB/trace structure. > Change the dimensions, add cables and the profile changes. > > Counter-challange - Prove to me that traces DO NOT radiate. > > > > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx > [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Lee Ritchey > Sent: Sunday, October 19, 2003 5:06 PM > To: Larry Barnes; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Traces don't cause EMI - really? > > > I downloaded a copy of this paper a few minutes ago. The conclusions of > the paper do not state that microstrip traces emit significant EMI. All > that is stated is that the analysis and chamber measurements agree within > measurement accuracy of what little energy is detected. The actual amount > is not stated in the paper. There is certainly no claim that the detected > emissions are large enough to cause concern among EMC engineers. > > This is likely one of those cases where the difference is between > detectable and significant. There is no claim in this paper that the > emissions are significant, only detectable. > > If we are to accept that surface traces are significant sources of EMI, > there needs to be credible demonstration of this. The reason is, designers > are expected to expend cost avoiding microstrip traces. To do this, there > needs to be demonstrated emissions that are worth the extra cost to control. > > My challenge to the proponents of this claim is to provide this > demonstration. > > I and many others have designed hundreds, maybe thousands of PCBs with > traces on outer layers with all the products successfully passing all > emissions tests. That could not happen if these claims are true. > > Lee > > > > [Original Message] > > From: Larry Barnes <larry.barnes@xxxxxxxxxx> > > To: <si-list@xxxxxxxxxxxxx> > > Date: 10/18/2003 5:42:14 AM > > Subject: [SI-LIST] Re: Traces don't cause EMI - really? > > > > I just couldn't resist after all this discussion. I would refer you to = > > a study done by Dr. Dave Hill of NIST. I demonstrates that microstrips = > > indeed radiate. The title of the paper is "Radiated Emissions and = > > Immunity of Microstrip Transmission Lines: Theory and Reverberation = > > Chamber Measurements" IEEE Trans on EMC May 1996.=20 > > > > Larry > > > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > Lawrence C. Barnes > > QLogic Corporation > > Aliso Viejo, CA 92656 > > > > > > ------------------------------------------------------------------ > > 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 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 > > > > > > ------------------------------------------------------------------ > 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 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 > ------------------------------------------------------------------ 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 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