Hi All, I am new to the area of PDN measurement. I am trying to measure impedance of a plane with VNA using two ports technique( S21). I have concern about the location of two ports on the PCB. Which is the best way ? Probing points close to each other or far away from each other on the PCB? Thanks in advance for your response. Regards, Navroop ----- _______________________________________________ ------------------------------------------------------------------ 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