Formulae to calculate the propagation constants of two lossless coupled transmission lines in terms of the self and mutual inductances and capacitances per unit length can be found in the paper by Tripathi in the February 1977 edition of IEEE Trans. on Microwave Theory and Techniques. Replacing L by R+jwL and C by G+jwC results in formulae to calculate the propagation constants of two lossy coupled transmission lines. For single ended transmission lines where gamma=sqrt((R+jwL)(G+jwC)) an approximation of the attenuation constant can be calculated using Taylor series and this procedure is detailed in Pozar. Has anyone calculated approximations for the attenuation constants for both the c and pi modes of two lossy coupled transmission lines using Taylor series? The math is horrendously difficult and I can't seem to separate out the phase constant component from inside the square root. I hope somebody can help me. ------------------------------------------------------------------ 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