directivity plot in matlab

hi friends

can u tell me how i can get gain in dB,beamwidth and directivity of a radiation pattern. I am using HFSS,it gives very large values because it does not consider reflected powers.

I want to plot it on MATLAB. i get radiation patterns of azimuth and vertical planes by ploting equations from BOOK.

how i could justify the gain,directivity and beamwidth as i just get a plot.

plz help em out.
Regards