Hello,
New boy here... I'm using NI Multisim 10 (Education Edition) to simulate an antenna matching network and the variation of values of components. The network consists of a loading inductor of +j9.405 in series with a resistance of 0.05 Ohm (loss) shunted with a series circuit consisting of a 1.7088 Ohm resistance (Rg), a capacitive reactance of -j307 (Xa) and an antenna tuning inductance (+j297.916). This gives a drive-point impedance 'looking in' of 48.625 +j0.005.
I'm entering the component values to obtain the aforementioned reactances at the frequency concerned.
When I calculate the equivalent value of the R-L-C arm of the circuit I get an equivalent of 1.7088 in series with a capacitive reactance of Xl - Xc or -j9.084, and when I use this equivalent component value, the network works fine: measured current is correct and the circuit behaves as expected.
However...
When I use the three discrete series values of 1.7088 Ohm, the capacitor that equates to -j 307 and the inductor that equates to +j 297.916, the circuit misbehaves and the network current reads some ridiculous figure! Why is this? It's like Multisim doesn't recognise that a series R-L-C circuit equates to an equivalent series R-C circuit after the reactances of L and C cancel, leaving an overall capacitive reactance shunted with a series R-L network.
I've tried basic components and variable components. I don't have much luck with the 'RF components' as I can't put the values in. I've never used simulation software in my life so I might be missing something obvious (but not to me) here.
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Kind Regds,
R.
