Nobody knows :-) Seriously, for EMC purposes, the electric (E) field radiation levels are measured in the far-field e.g. at a distance of 10 meters from the radiation source. If you have two (or more) electromagnetic field radiation sources, the sum of their radiated E-field at a far-field point is a spacial and temporal vector sum which depends on many things. For example, if the two radiation sources have orthogonal radiation patterns e.g. the point of maximum radiation of one source lies along the x-axis and the other along the y- axis, if the far-field point where you measure the E-field is along the x-axis, the total measured E-field will probably be just the maximum E-field of the first source (certainly not the linear sum of the two maxima). You also mentioned "system level" - and I'm sure you know that all systems are not created equal! A system can have other factors that affect field interactions making it so difficult to determine the best way to aggregate radiated E-field from multiple sources. A printed circuit board with many nets, operating at various frequencies, is a very complex radiation system by itself. When you have many of those boards, say in a shelf, you've compounded the problem even more. That's why I said at the beginning, nobody would know how to sum the radiated fields unless you're very specific on many things. In the 90's there were many tools that were claiming that they could predict radiated emission levels from printed circuit boards. Those tools failed primarily because of the prediction complexity that I've mentioned above. Best regards. Hassan. On Mar 13, Darshan Mehta <darshanmehta2k@xxxxxxxxx> wrote: > > Hello Everybody, > > I have one very basic question about EMC Analysis. If we have 2 nets in > design, CLK1 and CLK2, both switching at 200 MHz. If we see Electro-Magnetic radiation of 100 dB from CLK1 and 105 dB radiation from CLK2, what will be the EMI radiation level at System level? Thanks in Advance! > > Best Regards, > Darshan Mehta > > > --------------------------------- > Yahoo! Mail > Bring photos to life! New PhotoMail makes sharing a breeze. > ------------------------------------------------------------------ > 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: > <a > href='//www.freelists.org/webpage/si-list'>//www.freelists.org/webpage/si- list</a> > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > List FAQ wiki page is located at: > <a > href='http://si-list.org/wiki/wiki.pl?Si-List_FAQ'>http://si- list.org/wiki/wiki.pl?Si-List_FAQ</a> > > List technical documents are available at: > <a href='http://www.si-list.org'>http://www.si-list.org</a> > > List archives are viewable at: > <a href='//www.freelists.org/archives/si- list'>//www.freelists.org/archives/si-list</a> > or at our remote archives: > <a href='http://groups.yahoo.com/group/si- list/messages'>http://groups.yahoo.com/group/si-list/messages</a> > Old (prior to June 6, 2001) list archives are viewable at: > <a > href='http://www.qsl.net/wb6tpu'>http://www.qsl.net/wb6tpu</a> > > > ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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