ViPEC is a powerful tool for the analysis of high frequency, linear
electrical networks. It takes a schematic description of the electrical
network and performs a linear analysis in the frequency domain. The output
is in the form of port parameters (S, Y or Z) with results presented on a
user defined grid, Smithchart or table. It can also be used to compute
other characteristics like stability factors and group delay.

ViPEC supports various lumped elements (capacitors, resistors etc.) as well
as distributed networks like transmission lines, microstrip and stripline
structures. Two port data files are also supported (e.g. the 2-port frequency
parameters of various RF transistors as supplied by the manufacturer). The
component library is under constant development with new elements added at
regular intervals.

WWW: http://vipec.sourceforge.net/