RLC equivalent model and Impedance Smith Chart
That characteristic looks awfully like a parallel RLC circuit. At resonance the LC part becomes infinity and, because it is shunted with R, the effective impedance is R, possibly a 470 ohm resistor. At DC and low frequencies the inductor dominates with its low impedance and, if you went significantly higher than 1 GHz the parallel capacitance would dominate and start to act as a low impedance shunt. 

Below is just a convenient graph I found for a parallel RLC circuit: -


The difference between series and parallel resonance is shown side-by-side here: -



Picture from here.