Hi Virendra, I have done a similar project before. The way I did it is to treat the whole two-port network as a series impedance network. First You need to have proper calibration (TRL or others) to remove the effect of SMA connectors and traces. Then convert [S](2x2) to [Z](2x2). Since it is a series network, it can be approximated as Z =3D R + jX =3D Z11 + Z22 - Z21 - Z12 Then you can use circuit simulator (I used AWR's Microwave Office) to run the curve fitting to find the best values of R, L, C to match both R and X over the whole frequency band.=20 In addition, Murata's website has a tool you can download to see their model:=20 http://www.murata.com/designlib/mcsil.html Hope this will help. Regards, Ming -- Ming J. Tsai, Ph.D. Staff Hardware Development Engineer Product Technology - Hardware Design Group XILINX Telephone: 408-626-6260 E-Mail: ming.tsai@xxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Virendra Sent: Thursday, May 26, 2005 11:47 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] S11 or S21 Hello All, I am trying to measure the esl of a ceramic capacitor. I have a test board of 2"x 2" for this. I have SMA connectors connected to two sides of the test board.=20 Now to extract the esl of the capacitor, is it best to measure the S11 or S21.=20 Given that S21 gives lesser measurement errors does it still make sense to measure S21 when the two connectors are 2" apart? thanks in advance, virendra =09 __________________________________ Do you Yahoo!?=20 Yahoo! Mail - Helps protect you from nasty viruses.=20 http://promotions.yahoo.com/new_mail ------------------------------------------------------------------ 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