From: kochab <kochab@gm...>  20070513 18:04:12

solved!!! > > > > The problem with DET is that it is a nonlinear amplifier, actually a > > square law detector, for which I have an experimental transfer > > function between input power (W) and output Volts. > > Therefore I cannot use the 2 port Sparameters component because it > > works between input signal (V) and output signal (V). > > Therefore I would need to compute the power, V^2/50 and then apply the > > experimental transfer function which characterize the detector. > > Is there a way to do this in QUCS? > > Hm. In fact Sparameters determine ratios of power waves (not voltages!). Working at normalized impedance should be the same > The S21 (you seem to be interested in this) is proportional sqrt(P2/P1) at > given input and output impedance. So I propose to: > > with given transferfunction: Vout = f(Pin) > > to normalize Vout to an output power and then convert it to an Sparameter. Thanks, it worked: the transfer function (everything is a function of frequency) I have is v_out=tf * Pin while S21 is sqrt(Pout)= S21 * sqrt(Pin) therefore making the square root of the first equation: sqrt(Vout) = sqrt(tf) * sqrt(Pin) therefore the S21 is just the sqrt of tf and the result I get is the sqrt of Vout > Does this help?, > Stefan. A lot, thanks, Andrew 