# [SI-LIST] Re: Question about S-parameter and ABCD matrix

*From*: "Saoer Sinaga" <saoer.sinaga@xxxxxxxxx>*To*: si-list@xxxxxxxxxxxxx*Date*: Fri, 2 May 2008 09:21:38 +0200

Hi Sid, This question is actually originated from TRL calibration technique. In Pozar's book, it is written (in terms of ABCD matrix): [Measurement]=[Error]*[DUT]*inv[Error] But I would say, suppose: [Error]=[A,B;C,D], then [Measurement]=[A,B;C,D]*[DUT]*[D,B;C,A] regards, Saoer On Thu, May 1, 2008 at 9:20 PM, Sid Singh <siddharth019@xxxxxxxxx> wrote: > Saeor, > The answer lies in definition of ABCD matrix. They are used for > correlating inout voltage/current to output side. > [v1, i1] = [A, B ;C, D] * [v2, -i2] > > When you swap the I/O you end up rearraging above matrix equation with v2 > and i2 on LHS. The math will result in inverse of ABCD matrix being the > multiplier coefficient. > [v2, i2] = inv { [A, B ;C, D] } * [v1, -i1] > > For Scattering parameters the math is more intutive since they represent > the ratio of reflected vs incident waveform assuming matched termination at > other port. > > Sid. > > > > On 5/1/08, Saoer Sinaga <saoer.sinaga@xxxxxxxxx> wrote: > > > Hi all, > > I am not really sure if this is a relevant question for this forum. > > Suppose I have a two-port non-symmetric passive network whose S-par is > > Sx=[S11,S12;S21,S22]=[S11,S12;S12,S22]. > > Let's say the ABCD matrix of this network is Ax=[A,B;C,D]. > > > > If I rotate the device 180 degree, meaning port2 becomes port1 and vice > > versa, then the S-parameter would be Sy=[S22,S12;S12,S11]. Hence, the > > ABCD > > matrix would then be Ay=[D,B;C,A]. > > > > Am I missing something here? > > In the "Microwave Engineering" by David M. Pozar book, it is written > > that > > Ay=inverse[Ax]. > > > > regards, > > Saoer > > NXP Semiconductors > > > > > > ------------------------------------------------------------------ > > 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: > > http://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: > > http://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 > > > > > > > ------------------------------------------------------------------ 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: http://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: http://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

**Follow-Ups**:**[SI-LIST] Re: Question about S-parameter and ABCD matrix***From:*Yang, Long

**References**:**[SI-LIST] Question about S-parameter and ABCD matrix***From:*Saoer Sinaga

**[SI-LIST] Re: Question about S-parameter and ABCD matrix***From:*Sid Singh

## Other related posts:

- » [SI-LIST] Question about S-parameter and ABCD matrix
- » [SI-LIST] Re: Question about S-parameter and ABCD matrix
- » [SI-LIST] Re: Question about S-parameter and ABCD matrix
- » [SI-LIST] Re: Question about S-parameter and ABCD matrix