Hi Ed: F elements are current-controlled-current-sources, and they are a way of expressing mutual inductance. F elements are good for two reasons: (a) It is easier to represent than K elements, because the direction of coupling is hard to work out when you have n-coupled inductors. (b) Some versions of SPICE have trouble when many mutual inductance elements are in a circuit. If you draw yourself a circuit diagram for the CCCS connections in a simple SPICE subcircuit generated by Ansoft, you will realize that there is no approximations made while using the F-element to represent mutual inductnace ... ie it is a theoratically correct substitution. Just a small arithematic excercise to figure out a transformation from K to F. I believe Ansoft has a paper on this, I suggest you ask them to provide you a copy. Regards, - Neeraj. National Semiconductor Corporation http://www.national.com, NYSE: NSM > "Dr. Edward P. Sayre" wrote: > > Folks: > > Does anyone have specific experience of the satisfactory use of the Ansoft > Maxwell "F" dependent source modes to model multiple coupled inductors. I > am trying to do an RF crosstalk and transmission analysis using a Maxwell > derived model in SPICE. The answers do not reduce to the correct answers at > low frequencies or for that matter do they make sense at any other > frequency. Range of operation I am looking at is 50 MHz thru 1 GHz. > > I am looking for the basic derivation of how the "F" model (Current > controlled current source) expresses coupled inductors, or how it is > related to the coupled transformer coupling coefficient "k" which is the > more conventional way of expressing coupled inductors. > > Thanks in advance - > > ed sayre > > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ > | NORTH EAST SYSTEMS ASSOCIATES, INC. | > | ------------------------------------- | > | "High Performance Engineering & Design" | > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ > | Dr. Ed Sayre e-mail: esayre@xxxxxxxx | > | NESA, Inc. http://www.nesa.com/ | > | Primrose Park Tel +1.978.392-8787 | > | 5 LAN Drive, Ste 200 Fax +1.978.392-8686 | > | Westford, MA 01886 | > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ > -- National Semiconductor Corporation 2900 Semiconductor Drive, M/S 19-100 Santa Clara, California 95051 http://www.national.com/, NYSE: NSM ------------------------------------------------------------------ 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