Suggest you start with Eric Bogatin's book 'Signal Integrity Made Easy' like I did (also a post graduate) then save the questions you have after reading the book for these guru's of the signal integrity world. It is an excellent book and a good read also. Anyone else go to the Cadence seminar Tuesday that I didn't get to meet? I was the younger looking of you 'seasoned' experts!! ;o) Hope this helps Mark -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Charles Harrington Sent: 12 May 2005 11:36 To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Discontinuities on PCB Hello, When a TEM (or quasi-TEM) signal propagating on a microstrip trace meets a discontinuity (e.g., a via) on a substrate at microwave frequencies, higher-order modes are excited at the discontinuity, leading to reflections. Can anyone tell me exactly what kind of modes are excited and why they are excited. How far away from the discontinuity can they propagate and how does this depend on the operating frequency. I'm a postgraduate student currently working on=20 discontinuities on PCB. My search for relevant literature led me to this list. So, I'll appreciate any help.=20 Charles. =09 Yahoo! Mail Stay connected, organized, and protected. Take the tour: http://tour.mail.yahoo.com/mailtour.html ------------------------------------------------------------------ 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: =20 //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 =20 ------------------------------------------------------------------ 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