I have also noticed that behavior, maybe this could mean that if you are designing for lower data rates, it can be worse to have larger anti-pad and thus higher impedance of the via! BR /Mark 2012/4/23, Pehr Andersson <andersson.pehr@xxxxxxxxx>: > Hello fellow SI engineers! > I have noticed when running some simulation of vias, that by varying > anti-pad diameter, but keeping other parameters intact, that the return > loss for lower frequencies is higher then for case when the anti-pad is > smaller. > But for the higher frequencies there is an opposite effect, the return loss > decreases with the increasing anti-pad diameter. > I have included the picture that shows this effect. > > What is physical explanation for this effect? > > Why do RL increase for larger anti-pad compared to via with smaller > anti-pad diameter, when the frequency is < 5GHz ? > > Also why do the return loss decreases for the via with larger anti-pad > diameter compared to via with smaller anti-pad diameter, for f > 5GHz ? > > > Best regards, Pehr > > > > ------------------------------------------------------------------ > 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 forum is accessible at: > http://tech.groups.yahoo.com/group/si-list > > List archives are viewable at: > //www.freelists.org/archives/si-list > > 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu