impedance

[F8VOA]

How to mesure IN/OUT impedances (Z)  of HF circuits ?

[mbb25]

You measure the impedance of RF circuits using a VNA.  This document gives a good primer:

      http://download.ni.com/evaluation/rf/Introduction_to_Network_Analyzer_Measurements.pdf

Section 1 specifically talks about impedance.

[F8VOA]

Thanks for the info . I'm a LT-Spice user and in LTSpice it's  easy to mesure impadances of a HF-circuit . Do we have a tool in Multisim to do the same job ?

[mbb25]

Aha.  I figured I might have misunderstood your question.

I'm not as familiar with multisim.  This forum is more for RF hardware than software.  There's a separate multisim and ultiboard discussion forum where you might find people with more multisim expertise:

   http://forums.ni.com/t5/Multisim-and-Ultiboard/bd-p/370

Although I can see why you'd ping this group.  Yours is a RF-specific multisim question.  It might be worth pinging both.

I did turn up this page:

   http://digital.ni.com/public.nsf/allkb/9F8D30235DE3EC0186257592006B23A2

I don't have any experience using the above technique for RF circuits, however.