=20 >But at attenuation factor, there are conductor loss(skin effect) and dielectric loss. >How can I distinguish each other? =20 Dear HK Kim: The PCB trace losses include conductor and dielectric losses. The conductor losses can be decomposed as DC resistive plus skin effect losses. The Ohmic losses are frequency independent while the skin effect losses vary with square root of frequency. =20 The dielectric losses are proportional to frequency. At sufficiently high frequencies (exceeding ~ 1.0 GHz) for typical PCB trace dimensions, the dielectric losses can become the dominant loss mechanism. These transmission line losses can adversely influence signal rise time, amplitude,=20 noise margins and timing. Best Regards, Abe Riazi ServerWorks=20 =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 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