How to obtain the bandwidth from an sparameters() imported file?

When it comes to antennas, we require the bandwidth from obtained S11 readings, preferably below -10dB (Click here for more info). This is the frequency range at which the reflection coefficient is less than a certain magnitude (in most cases -10dB). The S11 plot can easily be generated using the code shown below. I will attach this .s1p file.

S = sparameters('50.s1p');
rfplot(S);

Which will give a plot as shown below.

Is there a Matlab code which will display the bandwidth for frequencies with magnitude less than -10dB? If I can atleast find out what the magnitude is at a specific frequency, I can calculate the bandwidth myself.