I am not sure why skin effect will play a role in group delay. Rather variation of dielectric of Fr-4 over this wide range should play a role. What is the definition of almost flat? :) -Qazi -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Neo Sent: Tuesday, June 02, 2009 2:29 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Group Delay of FR4 Trace Hi, I recently did a simulation on a 40inch FR4 channel. The group delay is calculated with the derivative of sdd21(phase). I'm surprised to find that the group delay is almost flat from 1-10GHz. Shouldn't it have some slope due to skin effect? Regards, Neo ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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