Hi I am working on SOI(silicon on insultor) with silicon (Epsilon r = 11.9 and h= 550 micron)and then on top of this is Sio2 (Epsilon r = 4 and h= 8 micron).Then is the metal layer(copper) .A part of the metal structure is coplanar strips and I am trying to find out the charactersitic impedance of the cps.For that I need to know the effective dielectric constant .I am using the equations from waddell 's design handbook.Confusion is which Epsilon r to be used in the equations..(11.9 or 4 ) Also for "h" do I just use 558 micron(by simply adding both the heights) and why? appreciate all the info regarding this.. Thanks Atif --------------------------------- Do you Yahoo!? Free online calendar with sync to Outlook(TM). ------------------------------------------------------------------ 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 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