Yes you would get a loss in both cases.. First option is more preferable... Otherwise in second option, overlap the differential signal in opposite polarity. i.e 2 layer +- 3 later -+ Cheers, Deepak -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Haller, Robert Sent: Thursday, August 05, 2010 3:49 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Insertion Loss, Return Loss, ILD, UNi versus Dual stripline I have 2 Diff pairs in the same dielectric Material (ISO370HR). One is Uni Stripline, One is Dual Stripline. Aside from the potentially different core/Prepreg material, resin content, glass weave (etc), and they are the Same Copper Geometry (say 4 mil line/7 mil space) and have the same impedance, same DC resistance will I be able to observe a difference in Insertion Loss, Return Loss, or Insertion Loss Deviation ? GND --------------- GND -------------- Sig - - SIG - - GND ---------------- SIG - - GND --------------- Regards Bob Robert Haller Architect Engineer, Switching Enterasys Networks Phone: +1 978 684 1340 Fax: +1 978 684 1499 E-mail: rhaller@xxxxxxxxxxxxx<mailto:gnigg@xxxxxxxxxxxxx> Web: www.enterasys.com<http://www.enterasys.com/> ------------------------------------------------------------------ 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 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu The information contained in this message may be confidential and legally protected under applicable law. The message is intended solely for the addressee(s). If you are not the intended recipient, you are hereby notified that any use, forwarding, dissemination, or reproduction of this message is strictly prohibited and may be unlawful. If you are not the intended recipient, please contact the sender by return e-mail and destroy all copies of the original message. ------------------------------------------------------------------ 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 Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu