calculate imaginary capacitance
if you have network analyzer , you can use S parameters to figure out the L,C,R
you can use S11 at very low frequency, in ehich the parasitic L is small and reactance is capacitive , then the imaginary part of it is C.
at very high freq teh C is out and L is dominant in imaginary part of S11.
by S21 you can measure the series R,
another complemantary methose is by looking at resonant freq.
by sweeping from 0.1 Ghz to 4GHz the first resonant freq is series resonant freq which represent a series R and C and L, second resonant freq which is normally higher , is parallel resonant freq which caused by parasitic L and C
Mehdi