Use the linspace function to create the ‘f’ vector:
I suspect that ‘zin’ should instead be:
and likely also needs to be a function of ‘w’. I leave that to you.
(When I made the necessary other corrections and ran your code, there appears to be a match at 450 MHz.)
EDIT — (20 Feb 2020 at 20:36)
The imaginary parts are ignored in the plot if you plot ‘gamma’. If you instead plot ‘agamma’ there is no problem.
For that reason, also use ‘agamma’ when you calculate the values in dB.