Oscillator nodes impedance simulations

Hello everybody,

I would like to simulate in ADS the impedance seen from the different components of a Pierce oscillator with the Harmonic Balance simulator. So far I simply calculated the magnitude of the voltage over current ratio, but I am not getting consistent results. When I calculate mag(V)/mag(I) for the first harmonic the results look a little more realistic, but I am not sure if the procedure is correct. So, I was wondering if you could give me some hint to better carry out this kind of analysis.
Many thanks in advance for any help!